A Statistical Framework to Interpret Individual Response to Intervention: Paving the Way for Personalized Nutrition and Exercise Prescription

A Review of the Validity and Reliability of Accelerometer-Based Metrics From Upper Back-Mounted GNSS Player Tracking Systems for Athlete Training Load Monitoring

ABSTRACT

Dawson, L, Beato, M, Devereux, G, and McErlain-Naylor, SA. A review of the validity and reliability of accelerometer-based metrics from upper back-mounted GNSS player tracking systems for athlete training load monitoring. J Strength Cond Res 38(8): e459-e474, 2024-Athlete load monitoring using upper back-mounted global navigation satellite system (GNSS) player tracking is common within many team sports. However, accelerometer-based load monitoring may provide information that cannot be achieved with GNSS alone. This review focuses on the accelerometer-based metrics quantifying the accumulation of accelerations as an estimation of athlete training load, appraising the validity and reliability of accelerometer use in upper back-mounted GNSS player tracking systems, the accelerometer-based metrics, and their potential for application within athlete monitoring. Reliability of GNSS-housed accelerometers and accelerometer-based metrics are dependent on the equipment model, signal processing methods, and the activity being monitored. Furthermore, GNSS unit placement on the upper back may be suboptimal for accelerometer-based estimation of mechanical load. Because there are currently no feasible gold standard comparisons for field-based whole-body biomechanical load, the validity of accelerometer-based load metrics has largely been considered in relation to other measures of training load and exercise intensity. In terms of convergent validity, accelerometer-based metrics (e.g., PlayerLoad, Dynamic Stress Load, Body Load) have correlated, albeit with varying magnitudes and certainty, with measures of internal physiological load, exercise intensity, total distance, collisions and impacts, fatigue, and injury risk and incidence. Currently, comparisons of these metrics should not be made between athletes because of mass or technique differences or between manufacturers because of processing variations. Notable areas for further study include the associations between accelerometer-based metrics and other parts of biomechanical load-adaptation pathways of interest, such as internal biomechanical loads or methods of manipulating these metrics through effective training design.

Acute Effects of Intracontrast Rest After Back Squats on Vertical Jump Performance During Complex Training

ABSTRACT

Houlton, LJ, Moody, JA, Bampouras, TM, and Esformes, JI. Acute effects of intracomplex rest after back squats on vertical jump performance during complex training. J Strength Cond Res XX(X): 000-000, 2024-Postactivation performance enhancement and complex-contrast sets are prevalent in sports science research. Typical complex-contrast sets consist of heavy back squats, an intracontrast rest period (ICRP) and vertical jumps (countermovement jumps [CMJs], or squat jumps [SJs]). Propulsive impulse (Jprop) is considered the leading indicator of jump performance. However, studies evaluating jump performance during complex-contrast sets use jump height as the primary performance measure, limiting insight into ICRP's effect on jump performance. We assessed the effect of a 3 repetition maximum (3RM) back squat and 6 ICRPs on vertical jump Jprop and associated force-time components. Fourteen subjects completed 12 experimental conditions, assigned equally to 4 testing sessions. Independent variables, in a 6 × 2 randomized, counterbalanced design, were ICRP (0, 60, 120, 180, 240, 300 seconds; ICRP0, ICRP60, ICRP120, ICRP180, ICRP240, ICRP300, respectively) and vertical jump (CMJ and SJ). Conditions consisted of baseline vertical jumps, followed by 3 back squat repetitions at 100% 3RM, an ICRP and experimental jumps. Symmetrized percentage changes between experimental and baseline jumps were assessed using repeated measures analysis of variance (ANOVA) and pairwise effect sizes. Results showed significant effects (p ≤ 0.05) on CMJ average rate of force development (RFD) between ICRP0 and ICRP120 and ICRP0 and ICRP300. Pairwise comparisons showed medium and large effect sizes for and increases in CMJ RFD (g = 0.83-2.69) whereas SJ RFD decreased (g = 0.81-2.57). Small effect sizes were found for Jprop, peak force, and mean force. Results suggest limited change in Jprop (g = 0.01-0.58), but back squats may potentiate RFD via the stretch-shortening cycle.

Responsiveness of functional performance and muscle strength, power, and size to resistance training: A systematic review

There is a recent and growing interest in assessing differential responders to resistance training (RT) for diverse outcomes. Thus, the individual ability to respond to an intervention for a specific measurement, called responsiveness, remains to be better understood. Thus, the current study aimed to summarize the available information about the effects of RT on functional performance and muscle strength, power, and size in healthy adults, through the prevalence rate in different responsiveness classifications models. A systematic review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) and was registered at the International Prospective Register of Systematic Reviews (PROSPERO, CRD42021265378). PubMed/MEDLINE, Scopus, and Embase databases were systematically searched in October 2023. A total of 13 studies were included, totaling 921 subjects. Only two studies presented a low risk of bias. Regarding the effectiveness of RT, the prevalence rate for non-responders ranged from 0% to 44% for muscle strength, from 0% to 84% for muscle size, and from 0% to 42% for functional performance, while for muscle power, the only study found showed a responsiveness rate of 37%. In conclusion, a wide range of differential responders is described for all variables investigated. However, the evidence summarized in this systematic review suggested some caution while interpreting the findings, since the body of evidence found seems to be incipient, and widely heterogeneous in methodological and statistical aspects.

Increasing aerobic exercise intensity fails to consistently improve the glycemic response in people living with prediabetes or type 2 diabetes mellitus: the INTENSITY trial

Some individuals with prediabetes or type 2 diabetes mellitus (T2DM) who engage in exercise will not experience the anticipated improvements in glycemic control, referred to as non-responders. Increasing exercise intensity may improve the proportion of individuals who become responders. The objectives were to (i) identify responders and non-responders based on changes in glycated hemoglobin (HbA1c) in individuals with prediabetes or T2DM following 16 weeks of aerobic exercise; (ii) investigate if increasing exercise intensity enhances the responders' status for individuals not previously responding favourably to the intervention. Participants (n = 40; age = 58.0 years (52.0-66.0); HbA1c = 7.0% (6.0-7.2)) engaged in a two-phase, randomized study design. During phase one, participants performed 16 weeks of treadmill-based, supervised, aerobic exercise at 4.5 metabolic equivalents (METs) for 150 min per week. Thereafter, participants were categorized as responders, non-responders, or unclear based on the 90% confidence interval above, below, or crossing a 0.3% reduction in HbA1c. For phase two, participants were randomized to a maintained intensity (4.5 METs) or increased intensity (6.0 METs) group for 12 weeks. Following phase one, two (4.1%) participants were categorized as responders, four (8.2%) as non-responders, and 43 (87.7%) as unclear. Following phase two, two from the increased intensity group and one from the maintained intensity group experienced an improvement in response categorization. There were no significant between or within group (maintained vs. increased) differences in HbA1c. For most people with prediabetes or T2DM, increasing exercise intensity by 1.5 METs does not improve response categorization.

Blood pressure responsiveness to resistance training in the hypertensive older adult: a randomized controlled study

Different lifestyle changes have been employed to improve clinical hypertension. However, there is scarce evidence on the blood pressure responsiveness to resistance training (RT) in hypertensive older adults. Consequently, little is known about some participants clinically reducing blood pressure and others not. Thus, we investigate the effects and responsiveness of RT on blood pressure in hypertensive older adults. We secondarily evaluated the biochemical risk factors for cardiovascular disease and functional performance. Older participants with hypertension were randomly assigned into RT (n = 27) and control group (n = 25). Blood pressure, functional performance (timed up and go, handgrip strength, biceps curl and sit-to-stand), fasting glucose, and lipid profiles were evaluated preintervention and postintervention. The statistic was performed in a single-blind manner, the statistician did not know who was the control and RT. RT was effective in reducing systolic blood pressure (SBP) (pre 135.7 ± 14.7; post 124.7 ± 11.0; P  < 0.001) and the responses to RT stimuli varied noticeably between hypertensive older adults after 12 weeks. For example, 13 and 1 responders displayed a minimal clinical important difference for SBP attenuation (10.9 mmHg) in the RT and control groups, respectively. RT improved the functional performance of older people with hypertension, while no differences were found in biochemical parameters (triglycerides, HDL, LDL, fasting glucose) after 12 weeks. In conclusion, responses to RT stimuli varied noticeably between hypertensive individuals and RT was effective in reducing SBP.

The Effect of Time-Equated Concurrent Training Programs in Resistance-Trained Men

The purpose of this investigation was to compare the effects of three different concurrent training (CT) programs and a resistance training (RT) program. Twenty-three resistance trained men (age: 24 ± 3 years) were randomized into four groups: concurrent RT and high intensity interval cycling (CTH, n = 6), concurrent RT and moderate intensity continuous cycling (CTM, n = 5), RT and barbell circuit training (RTC, n = 6), or RT only (RT, n = 6). Back squat and bench press strength, quadriceps, and pectoralis muscle thickness, VO2peak, and maximum workload (Wmax, Watts) were assessed. Squat strength gains were meaningful in all groups and comparable among CTH (16.88 kg [95% CrI: 11.15, 22.63]), CTM (25.54 kg [95% CrI: 19.24, 31.96]), RTC (17.5 kg [95% CrI: 11.66, 23.39]), and RT (20.36 kg [95% CrI: 15.29, 25.33]) groups. Bench press strength gains were meaningful in all groups and comparable among CTH (11.86 kg [95% CrI: 8.28, 15.47]), CTM (10.3 kg [95% CrI: 6.49, 14.13]), RTC (4.84 kg [95% CrI: 1.31, 8.47]), and RT (10.16 kg [95% CrI: 7.02, 13.22]) groups. Quadriceps hypertrophy was meaningful in all groups and comparable among CTH (2.29 mm [95% CrI: 0.84, 3.76]), CTM (3.41 mm [95% CrI: 1.88, 4.91]), RTC (2.6 mm [95% CrI: 1.17, 4.05]), and RT (2.83 mm [95% CrI: 1.55, 4.12]) groups. Pectoralis hypertrophy was meaningful in CTH (2.29 mm [95% CrI: -0.52, 5.1]), CTM (5.14 mm [95% CrI: 2.1, 8.15]), and RTC (7.19 mm [95% CrI: 4.26, 10.02]) groups, but not in the RT group (1 mm [95% CrI: -1.59, 3.59]); further, between-group contrasts indicated less pectoralis growth in the RT compared to the RTC group. Regarding cardiovascular outcomes, only the RTH and RTM groups experienced meaningful improvements in either measure (VO2peak or Wmax). These data suggest that the interference effect on maximal strength and hypertrophy can be avoided when the aerobic training is moderate intensity cycling, high intensity cycling, or a novel barbell circuit for ~one hour per week and on non-RT days. However, the barbell circuit failed to elicit meaningful cardiovascular adaptations.

Chronic Effects of Inter-Set Static Stretching on Morphofunctional Outcomes in Recreationally Resistance-Trained Male and Female

Purpose: The purpose of this study was to compare the effects of resistance training (RT) with inter-set static stretching (IS) versus traditional RT (TRT) on morphofunctional outcomes in recreationally resistance-trained male and female. Methods: Twenty-two recreationally-trained subjects were allocated to IS group (n = 12) or TRT (n = 10) and completed eight weeks of RT. The only difference between the groups was that IS group included static stretching between sets, while the TRT rested between the sets. Ultrasound images, dynamic and isometric strength tests for the elbow flexors and elbow extensors were evaluated pre- and post-intervention period. Results: Total training volume (TTV) was greater in TRT than IS (p = .031). TRT and IS caused similar increases in maximal dynamic and isometric strength. Fascicle length of the brachialis increased following TRT (p = .033); muscle thickness and the pennation angle of the distal portion of the triceps brachii increased following IS (p = .035 and p = .007, respectively). There were no significant changes in thickness and architecture for biceps brachii in either group. There were no significant differences between groups for any muscle strength and morphology outcome. Conclusion: IS negatively affects TTV but does not affect muscle strength and architecture of recreationally resistance-trained male and female.

Frequentist, Bayesian Analysis and Complementary Statistical Tools for Geriatric and Rehabilitation Fields: Are Traditional Null-Hypothesis Significance Testing Methods Sufficient?

Null hypothesis significant testing (NHST) is the dominant statistical approach in the geriatric and rehabilitation fields. However, NHST is routinely misunderstood or misused. In this case, the findings from clinical trials would be taken as evidence of no effect, when in fact, a clinically relevant question may have a "non-significant" p-value. Conversely, findings are considered clinically relevant when significant differences are observed between groups. To assume that p-value is not an exclusive indicator of an association or the existence of an effect, researchers should be encouraged to report other statistical analysis approaches as Bayesian analysis and complementary statistical tools alongside the p-value (eg, effect size, confidence intervals, minimal clinically important difference, and magnitude-based inference) to improve interpretation of the findings of clinical trials by presenting a more efficient and comprehensive analysis. However, the focus on Bayesian analysis and secondary statistical analyses does not mean that NHST is less important. Only that, to observe a real intervention effect, researchers should use a combination of secondary statistical analyses in conjunction with NHST or Bayesian statistical analysis to reveal what p-values cannot show in the geriatric and rehabilitation studies (eg, the clinical importance of 1kg increase in handgrip strength in the intervention group of long-lived older adults compared to a control group). This paper provides potential insights for improving the interpretation of scientific data in rehabilitation and geriatric fields by utilizing Bayesian and secondary statistical analyses to better scrutinize the results of clinical trials where a p-value alone may not be appropriate to determine the efficacy of an intervention.

Higher resistance training volume offsets muscle hypertrophy nonresponsiveness in older individuals

The magnitude of muscle hypertrophy in response to resistance training (RT) is highly variable between individuals (response heterogeneity). Manipulations in RT variables may modulate RT-related response heterogeneity; yet, this remains to be determined. Using a within-subject unilateral design, we aimed to investigate the effects of RT volume manipulation on whole muscle hypertrophy [quadriceps muscle cross-sectional area (qCSA)] among nonresponders and responders to a low RT dose (single-set). We also investigated the effects of RT volume manipulation on muscle strength in these responsiveness groups. Eighty-five older individuals [41M/44F, age = 68 ± 4 yr; body mass index (BMI) = 26.4 ± 3.7 kg/m2] had one leg randomly allocated to a single (1)-set and the contralateral leg allocated to four sets of unilateral knee-extension RT at 8-15 repetition maximum (RM) for 10-wk 2 days/wk. Pre- and postintervention, participants underwent magnetic resonance imaging (MRI) and unilateral knee-extension 1-RM strength testing. MRI typical error (2× TE = 3.27%) was used to classify individuals according to responsiveness patterns. n = 51 were classified as nonresponders (≤2× TE) and n = 34 as responders (>2× TE) based on pre- to postintervention change qCSA following the single-set RT protocol. Nonresponders to single-set training showed a dose response, with significant time × set interactions for qCSA and 1-RM strength, indicating greater gains in response to the higher volume prescription (time × set: P < 0.05 for both outcomes). Responders improved qCSA (time: P < 0.001), with a tendency toward higher benefit from the four sets RT protocol (time × set: P = 0.08); on the other hand, 1-RM increased similarly irrespectively of RT volume prescription (time × set: P > 0.05). Our findings support the use of higher RT volume to mitigate nonresponsiveness among older adults.NEW & NOTEWORTHY Using a within-subject unilateral design, we demonstrated that increasing resistance training (RT) volume may be a simple, effective strategy to improve muscle hypertrophy and strength gains among older adults who do not respond to low-volume RT. In addition, it could most likely be used to further improve hypertrophic outcomes in responders.

Resistance training and inter-interindividual response differences on cardiorespiratory fitness in older adults: An ancillary meta-analysis of randomized controlled trials

Examine true inter-individual response differences (IIRD) as a result of resistance training on cardiorespiratory fitness in older adults. Data from a recent meta-analysis of 22 randomized controlled trials representing 552 men and women (292 resistance training, 260 control) ≥ 60 years of age were included. The primary outcome was cardiorespiratory fitness (VO2max) in ml.kg-1.min-1. Using the inverse variance heterogeneity (IVhet) model, statistically significant treatment effect (resistance training minus control) increases in VO2max in ml.kg-1.min-1 were found (mean, 1.8, 95% CI, 0.4 to 3.3 ml.kg-1.min-1, p = 0.01; Q = 82.8, p < 0.001; I2 = 74.6%, 95% CI, 61.6 to 83.3%; τ 2 =1.1). The 95% prediction interval (PI) was -0.8 to 4.5 ml.kg-1.min-1. However, no statistically significant IIRD was observed (mean, 0.6, 95% CI, -1.1 to 1.4 ml.kg-1.min-1; τ 2 =1.5). The 95% PI was -1.8 to 2.0 ml.kg-1.min-1. In conclusion, while progressive resistance training may increase VO2max in ml.kg-1.min-1, a lack of true resistance-training-associated IIRD exist.

Including supramaximal verification reduced uncertainty in VO2peak response rate

Many reports describe using a supramaximal verification phase-exercising at a power output higher than the highest power output recorded during an incremental cardiopulmonary test-to validate VO2max. The impact of verification phases on estimating the proportion of individuals who increased VO2peak in response to high-intensity interval training (HIIT) remains an underexplored area in the individual response literature. This analysis investigated the influence of same-day and separate-day verification phases during repeated measurements (incremental tests-INCR1 and INCR2; incremental tests + supramaximal verification phases-INCR1+ and INCR2+) of VO2peak on typical error (TE) and the proportion of individuals classified as responders (i.e., the response rate) following 4 weeks of HIIT (n = 25) or a no-exercise control period (n = 9). Incorporation of supramaximal verification consistently reduced the standard deviation of individual response, TE, and confidence interval (CI) widths. However, variances were statistically similar across all groups (p > 0.05). Response rates increased when incorporating either one (INCR1 to INCR1+; 24%-48%, p = 0.07) or two (INCR2 to INCR2+; 28%-48%, p = 0.063) supramaximal verification phases. However, response rates remained unchanged when either zero-based thresholds or smallest worthwhile difference response thresholds were used (50% and 90% CIs, all p > 0.05). Supramaximal verification phases reduced random variability in VO2peak response to HIIT. Compared with separate-day testing (INCR2 and INCR2+), the incorporation of a same-day verification (INCR1+) reduced CI widths the most. Researchers should consider using a same-day verification phase to reduce uncertainty and better estimate VO2peak response rate to HIIT.

Moderate to Vigorous Intensity Locomotor Training After Stroke: A Systematic Review and Meta-analysis of Mean Effects and Response Variability

BACKGROUND AND PURPOSE

This meta-analysis quantified mean effects of moderate to vigorous intensity locomotor training (LT mv ) on walking outcomes in subacute and chronic stroke, and the magnitude of variability in LT mv response.

METHODS

Databases were searched for randomized trials comparing LT mv with no intervention, nongait intervention, or low-intensity gait training. Comfortable gait speed (CGS), fastest gait speed (FGS), 6-minute walk test (6MWT), walking activity (steps per day), and adverse effect/event (AE) data were extracted. Pooled estimates were calculated for mean changes, AE relative risks, and the standard deviation of response (SD response ) to LT mv versus control groups, stratified by study chronicity where possible.

RESULTS

There were 19 eligible studies (total N = 1096): 14 in chronic stroke (N = 839) and 5 in subacute stroke (N = 257). Compared with control interventions, LT mv yielded significantly greater increases in CGS (chronic, +0.06 m/s [95% confidence interval (CI), 0.01-0.10]; subacute, +0.16 [0.12-0.19]; subacute vs chronic, P = 0.03), FGS (chronic, +0.07 m/s [0.02-0.13]; subacute, +0.21 [0.01, 0.41]; P = 0.04), and 6MWT (chronic, +33 m [24-42]; subacute, +51 [26-77]; P = 0.054) but not steps/day (+260 [-1159 to 1679]). There were no treatment-related serious AEs among 398 LT mv participants in 14 AE-reporting studies. SD response estimates indicated substantial response variability: CGS, 0.11 m/s [0.00-0.15]; FGS, 0.14 m/s [-0.00 to 0.20]; and 6MWT, 41 m [27-51].

DISCUSSION AND CONCLUSIONS

LT mv improves mean walking capacity outcomes in subacute and chronic stroke and does not appear to have high risk of serious harm. Response magnitude varies within and between chronicity subgroups, and few studies have tested effects on daily walking activity or non-serious AEs.Video Abstract available for more insights from the authors (see the Video, Supplemental Digital Content 1 available at: http://links.lww.com/JNPT/A452 ).

Are There Interindividual Responses of Cardiovascular Disease Risk Markers to Acute Exercise? A Replicate Crossover Trial

PURPOSE

Using a replicated crossover design, we quantified the response heterogeneity of postprandial cardiovascular disease risk marker responses to acute exercise.

METHODS

Twenty men (mean (SD) age, 26 (6) yr; body mass index, 23.9 (2.4) kg·m -2 ) completed four 2-d conditions (two control, two exercise) in randomized orders. On days 1 and 2, participants rested and consumed two high-fat meals over 9 h. Participants ran for 60 min (61 (7)% of peak oxygen uptake) on day 1 (6.5 to 7.5 h) of both exercise conditions. Time-averaged total area under the curve (TAUC) for triacylglycerol, glucose, and insulin were calculated from 11 venous blood samples on day 2. Arterial stiffness and blood pressure responses were calculated from measurements at baseline on day 1 and at 2.5 h on day 2. Consistency of individual differences was explored by correlating the two replicates of control-adjusted exercise responses for each outcome. Within-participant covariate-adjusted linear mixed models quantified participant-by-condition interactions and individual response SDs.

RESULTS

Acute exercise reduced mean TAUC-triacylglycerol (-0.27 mmol·L -1 ·h; Cohen's d = 0.29, P = 0.017) and TAUC-insulin (-25 pmol·L -1 ·h; Cohen's d = 0.35, P = 0.022) versus control, but led to negligible changes in TAUC-glucose and the vascular outcomes (Cohen's d ≤ 0.36, P ≥ 0.106). Small-to-moderate, but nonsignificant, correlations were observed between the two response replicates ( r = -0.42 to 0.15, P ≥ 0.066). We did not detect any individual response heterogeneity. All participant-by-condition interactions were P ≥ 0.137, and all individual response SDs were small with wide 95% confidence intervals overlapping zero.

CONCLUSIONS

Large trial-to-trial within-subject variability inhibited detection of consistent interindividual variability in postprandial metabolic and vascular responses to acute exercise.

Acute Effect of the "Zero Point" Method on Muscle Thickness and Muscle Damage in Trained Men

The "zero point" method allows for lower intensities for an exercise session without impairing the total training volume. This study aimed to compare the effects of the "zero point" versus the traditional method on muscle responses and muscle damage in trained men. Fifteen experienced men (age: 27.7 ± 6.4 years; body mass: 78.4 ± 11.4 kg; height: 174.8 ± 4.9 cm; experience: 5.86 ± 4.7 years; relative bench press strength: 1.38 ± 0.17 kg·kg-1) were subjected to two exercise protocols in a randomized order and separated by a week. The traditional and "zero point" methods were applied in the bench press, with loads of 70% and 50% of one repetition maximum (1RM), respectively, for 10 sets until concentric failure, with 3-min intervals between sets. The zero point method displayed a higher number of repetitions and time under tension than the traditional method, with no difference in the total training volume, echo intensity, algometry, lactate, and myoglobin. For the muscle thickness, no differences between the groups were presented, except for the deltoid muscle thickness, in which a higher post-training volume was observed compared to traditional training. The "zero point" method increases the demand on the deltoid muscles in the bench press exercise, but not on the pectoralis and triceps brachii.

Estimating individual health-related quality of life changes in low back pain patients

BACKGROUND

There is a need to evaluate different options for estimating individual change in health-related quality of life for patients with low back pain.

METHODS

Secondary analysis of data collected at baseline and 6 weeks later in a randomized trial of 749 adults with low back pain receiving usual medical care (UMC) or UMC plus chiropractic care at a small hospital at a military training site or two large military medical centers. The mean age was 31; 76% were male and 67% were White. The study participants completed the Patient-Reported Outcomes Measurement Information System (PROMIS®)-29 v 1.0 physical function, pain interference, pain intensity, fatigue, sleep disturbance, depression, anxiety, satisfaction with participation in social roles, physical summary, and mental health summary scores (T-scored with mean = 50 and standard deviation (SD) = 10 in the U.S. general population).

RESULTS

Reliability estimates at the baseline ranged from 0.700 to 0.969. Six-week test-retest intraclass correlation estimates were substantially lower than these estimates: the median test-retest intraclass correlation for the two-way mixed-effects model was 0. 532. Restricting the test-retest reliability estimates to the subset who reported they were about the same as at baseline on a retrospective rating of change item increased the median test-retest reliability to 0.686. The amount of individual change that was statistically significant varied by how reliability was estimated, and which SD was used. The smallest change needed was found when internal consistency reliability and the SD at baseline were used. When these values were used, the amount of change needed to be statistically significant (p < .05) at the individual level ranged from 3.33 (mental health summary scale) to 12.30 (pain intensity item) T-score points.

CONCLUSIONS

We recommend that in research studies estimates of the magnitude of individual change needed for statistical significance be provided for multiple reliability and standard deviation estimates. Whenever possible, patients should be classified based on whether they 1) improved significantly and perceived they got better, 2) improved significantly but did not perceive they were better, 3) did not improve significantly but felt they got better, or 4) did not improve significantly or report getting better.

The Between-Day Reliability of Correlation Properties of Heart Rate Variability During Running

The short-term scaling exponent of detrended fluctuation analysis (DFA-a1) of heart rate variability may be a helpful tool to assess autonomic balance as a prelude to daily, individualized training. For this concept to be useful, between-session reliability should be acceptable. The aim of this study was to explore the reliability of DFA-a1 during a low-intensity exercise session in both a non-fatigued and a fatigued condition in healthy males and females. Ten participants completed two sessions with each containing an exhaustive treadmill ramp protocol. Before and after the fatiguing ramp, a standardized submaximal low-intensity exercise bout was performed during which DFA-a1, heart rate, and oxygen consumption (VO2) were measured. We compared between-session reliability of all metrics prior to the ramps (i.e., non-fatigued status) and after the first ramp (i.e., fatigued status). Intraclass correlation coefficients (ICC) with 95% confidence intervals (CI), the standard error of measurement, and the smallest worthwhile change (SWC) were determined. The ICC and SWC pre fatiguing ramp were 0.85 (95% CI 0.39-0.96) and 5.5% for DFA-a1, 0.85 (0.38-0.96) and 2.2% for heart rate, and 0.84 (0.31-0.96) and 3.1% for VO2. Post fatiguing ramp, the ICC and SWC were 0.55 (0.00-0.89) and 7.9% for DFA-a1, 0.91 (0.62-0.98) and 1.6% for heart rate, and 0.80 (0.17-0.95) and 3.0% for VO2. DFA-a1 shows generally acceptable to good between-session reliability with a SWC of 0.06 and 0.07 (5.5-7.9%) during non-fatigued and fatigued conditions. This suggests that this metric may be useful to inform on training readiness.

The Kneeling Isometric Plantar Flexor Test: Preliminary Reliability and Feasibility in Professional Youth Football

Calf injuries are common in professional football; thus, the establishment of reliable and time-efficient methods of measuring the peak force capabilities of the plantar flexors with equipment that is accessible to football practitioners is valuable. In this study, we determined the preliminary reliability and feasibility of a new test, termed the kneeling isometric plantar flexion test (KIPFT), for footballers. Twenty-one male youth footballers (age = 17.8 ± 1.1 years, height = 182 ± 5 cm, weight = 77.6 ± 5.9 kg) from English League One football clubs completed three trials of the KIPFT on a wireless force plate at the end (2022-2023) and start (2023-2024) of the season. The within-session reliability of the peak force (relative to body weight) was good-excellent for both limbs and both occasions. On average, performance of the KIPFT took just over 1 min per limb and ~2 min to set up. The peak force values were larger for the non-dominant limbs only at the start versus the end of the season, but there were no between-limb differences. From these results, it was determined that (1) the KIPFT is feasible, (2) a minimum of 32 footballers would be required to establish its between-session reliability with ≥80% statistical power and (3) large-cohort normative data for the KIPFT may be best collected at the start of the football season.

Personalized redox biology: Designs and concepts

Personalized interventions are regarded as a next-generation approach in almost all fields of biomedicine, such as clinical medicine, exercise, nutrition and pharmacology. At the same time, an increasing body of evidence indicates that redox processes regulate, at least in part, multiple aspects of human physiology and pathology. As a result, the idea of applying personalized redox treatments to improve their efficacy has gained popularity among researchers in recent years. The aim of the present primer-style review was to highlight some crucial yet underappreciated methodological, statistical, and interpretative concepts within the redox biology literature, while also providing a physiology-oriented perspective on personalized redox biology. The topics addressed are: (i) the critical issue of investigating the potential existence of inter-individual variability; (ii) the importance of distinguishing a genuine and consistent response of a subject from a chance finding; (iii) the challenge of accurately quantifying the effect of a redox treatment when dealing with 'extreme' groups due to mathematical coupling and regression to the mean; and (iv) research designs and analyses that have been implemented in other fields, and can be reframed and exploited in a redox biology context.

Impact of cluster set resistance training on strength, functional capacity, metabolic and inflammatory state in older hemodialysis subjects: A randomized controlled clinical trial

BACKGROUND AND AIMS

Hemodialysis-associated neuromuscular dysfunction appears to be counteracted by resistance training (RT) in older patients with chronic kidney disease (CKD). Thus, the aim of the present study was to evaluate the impact of cluster-set RT protocol on anthropometric parameters, functional capacities, and biochemical variables in older patients with CKD.

METHODS AND RESULTS

Seventy-eight older patients (age: 57.55 ± 4.06 years) with CKD undergoing maintenance hemodialysis participated, and were randomly divided into control group (CG, N = 26), traditional RT (RT, N = 26) and cluster-set RT (RT-CS, N = 26) groups. Participants completed 24 weeks of RT three times per week, 1 h and 30 min before the hemodialysis session. Patients from the RT-CS group displayed increased adherence as compared to the RT group (66.35 % versus 61.73 %, p < 0.0001). There was an improvement of all anthropometric variables, handgrip strength, timed up and-go (TUG) and six-minute walking test (6MWT) following both training protocols when compared to control group and pre-intervention values. Fasting blood glucose decreased for both RT and RT-CS groups as compared with pre-intervention, without differences between training protocols and CG. Glycated hemoglobin, inflammatory cytokines, and triglycerides decreased in RT and RT-CS groups as compared with pre-intervention and CG, without differences between them. Furthermore, the RT-CS protocol resulted in a greater number of people who were responsive to training when compared to traditional training.

CONCLUSIONS

RT-CS is a clinically valuable tool to improve anthropometric parameters, handgrip strength, TUG, 6MWT, fasting blood glucose, and cytokines in CKD older patients.

The impact of progressive overload on the proportion and frequency of positive cardio-respiratory fitness responders

The proportion of individuals whose cardio-respiratory fitness change after endurance training does not exceed the test's measurement error can be 40 %. We determined if progressively increasing treadmill run intensity compared to maintaining the same run intensity, improved the responder proportion to a 6-week 20-minute treadmill training regimen. The intervention response standard deviation method estimated the proportion of responders attributable to progressively increasing run intensity. The mixed-effects model demonstrated V̇O2 peak improved significantly more in the progressive versus constant run intensity group. The proportion of V̇O2 peak responses above the smallest worthwhile change attributable to progressively increasing run intensity was 63.6 %.

Validity and reliability of Polar M400 GPS watches for measuring distances covered by team sports players

Monitoring locomotor demands in team sports becomes popular in professional and recreational daily activities. Precise measurements are main of importance in training routine. The aim of this study is three-fold: (i) analyze the validity of Polar M400 Global Positioning System (GPS) watches for measuring distances covered in team sports simulation cycle; (ii) testing inter-unit reliability of two devices attached during testing; and (iii) testing inter-session reliability for the same simulation cycle. Methods: Twenty-one team athletes (age: 24.5 ± 5.2 years; body mass: 71.8 ± 5.7 kg; height: 176.5 ± 4.3 cm) were tested in the team sport simulation cycle (TSSC). Two Polar M400 sport watches were used by each player on their wrists at the same time. The data obtained from Polar M400 were compared to the reference fixed distance of the TSSC to determine the watch validity. Inter-session reliability was also tested using the two watches in two different sessions. Results: No significant differences between the reference value and the watches (F = 1.086; p = 0.368; η p 2 ≤0.042) were found. The %CV (0.03-0.05%) and SEM (0.05-0.09) values found for all considered groups confirmed good levels of reliability of the Polar M400 to measure total distance. Conclusions: The Polar M400 is a valid and reliable watch for measuring the distances covered by team sport athletes. Both coaches and athletes can monitor the distances covered with accuracy and precision, through the use of the Polar M400 sport watch.

Heterogeneous Treatment Effects after Inspiratory Muscle Training during Recovery from Postacute COVID-19 Syndrome

PURPOSE

The objective of this study is to investigate whether heterogeneous treatment effects occur for changes in inspiratory muscle strength, perceived dyspnea, and health-related quality of life after 8 wk of unsupervised home-based inspiratory muscle training (IMT) in adults with postacute coronavirus disease 2019 (COVID-19) syndrome.

METHODS

In total, 147 adults with self-reported prior COVID-19 either completed an 8-wk home-based IMT intervention ( n = 111, 92 females, 48 ± 11 yr, 9.3 ± 3.6 months postacute COVID-19 infection) or acted as "usual care" wait list controls ( n = 36, 34 females, 49 ± 12 yr, 9.4 ± 3.2 months postacute COVID-19 infection).

RESULTS

Applying a Bayesian framework, we found clear evidence of heterogeneity of treatment response for inspiratory muscle strength: the estimated difference between standard deviations (SD) of the IMT and control groups was 22.8 cm H 2 O (75% credible interval (CrI), 4.7-37.7) for changes in maximal inspiratory pressure (MIP) and 86.8 pressure time units (75% CrI, 55.7-116.7) for sustained MIP (SMIP). Conversely, there were minimal differences in the SD between the IMT and the control group for changes in perceived dyspnea and health-related quality of life, providing no evidence of heterogeneous treatment effects. Higher cumulative power during the IMT intervention was related to changes in MIP ( β = 10.9 cm H 2 O (95% CrI, 5.3-16.8) per 1 SD) and SMIP ( β = 63.7 (32.2-95.3) pressure time units per 1 SD), clearly indicating an IMT dose response for changes in inspiratory muscle strength. Older age (>50 yr), a longer time postacute COVID-19 (>3 months), and greater severity of dyspnea at baseline were also associated with smaller improvements in inspiratory muscle strength.

CONCLUSIONS

Heterogeneous individual responses occurred after an 8-wk home-based IMT program in people with postacute COVID-19 syndrome. Consistent with standard exercise theory, larger improvements in inspiratory muscle strength are strongly related to a greater cumulative dose of IMT.

P1NP and β-CTX-1 Responses to a Prolonged, Continuous Running Bout in Young Healthy Adult Males: A Systematic Review with Individual Participant Data Meta-analysis

BACKGROUND

Circulating biomarkers of bone formation and resorption are widely used in exercise metabolism research, but their responses to exercise are not clear. This study aimed to quantify group responses and inter-individual variability of P1NP and β-CTX-1 after prolonged, continuous running (60-120 min at 65-75% V̇O2max) in young healthy adult males using individual participant data (IPD) meta-analysis.

METHODS

The protocol was designed following PRISMA-IPD guidelines and was pre-registered on the Open Science Framework prior to implementation ( https://osf.io/y69nd ). Changes in P1NP and β-CTX-1 relative to baseline were measured during, immediately after, and in the hours and days following exercise. Typical hourly and daily variations were estimated from P1NP and β-CTX-1 changes relative to baseline in non-exercise (control) conditions. Group responses and inter-individual variability were quantified with estimates of the mean and standard deviation of the difference, and the proportion of participants exhibiting an increased response. Models were conducted within a Bayesian framework with random intercepts to account for systematic variation across studies.

RESULTS

P1NP levels increased during and immediately after running, when the proportion of response was close to 100% (75% CrI: 99 to 100%). P1NP levels returned to baseline levels within 1 h and over the next 4 days, showing comparable mean and standard deviation of the difference with typical hourly (0.1 ± 7.6 ng·mL-1) and daily (- 0.4 ± 5.7 ng·mL-1) variation values. β-CTX-1 levels decreased during and up to 4 h after running with distributions comparable to typical hourly variation (- 0.13 ± 0.11 ng·mL-1). There was no evidence of changes in β-CTX-1 levels during the 4 days after the running bout, when distributions were also similar between the running data and typical daily variation (- 0.03 ± 0.10 ng·mL-1).

CONCLUSION

Transient increases in P1NP were likely biological artefacts (e.g., connective tissue leakage) and not reflective of bone formation. Comparable small decreases in β-CTX-1 identified in both control and running data, suggested that these changes were due to the markers' circadian rhythm and not the running intervention. Hence, prolonged continuous treadmill running did not elicit bone responses, as determined by P1NP and β-CTX-1, in this population.

Exploring interindividual differences in fasting and postprandial insulin sensitivity adaptations in response to sprint interval exercise training

Previous studies have concluded that wide variance in changes in insulin sensitivity markers following exercise training demonstrates heterogeneity in individual trainability. However, these studies frequently don't account for technical, biological, and random within-subject measurement error. We used the standard deviation of individual responses (SDIR) to determine whether interindividual variability in trainability exists for fasting and postprandial insulin sensitivity outcomes following low-volume sprint interval training (SIT). We pooled data from 63 untrained participants who completed 6 weeks of SIT (n = 49; VO2max: 35 (7) mL⋅kg-1⋅min-1) or acted as no-intervention controls (n = 14; VO2max: 34 (6) mL⋅kg-1⋅min-1). Fasting and oral glucose tolerance test (OGTT)-derived measures of insulin sensitivity were measured pre- and post-intervention. SDIR values were positive and exceeded a small effect size threshold for changes in fasting glucose (SDIR = 0.27 [95%CI 0.07,0.38] mmol⋅L-1), 2-h OGTT glucose (SDIR = 0.89 [0.22,1.23] mmol⋅L-1), glucose area-under-the-curve (SDIR = 66.4 [-81.5,124.3] mmol⋅L-1⋅120min-1) and The Cederholm Index (SDIR = 7.2 [-16.0,19.0] mg⋅l2⋅mmol-1⋅mU-1⋅min-1), suggesting meaningful individual responses to SIT, whilst SDIR values were negative for fasting insulin, fasting insulin resistance and insulin AUC. For all variables, the 95% CIs were wide and/or crossed zero, highlighting uncertainty about the existence of true interindividual differences in exercise trainability. Only 2-22% of participants could be classified as responders or non-responders with more than 95% certainty. Our findings demonstrate it cannot be assumed that variation in changes in insulin sensitivity following SIT is attributable to inherent differences in trainability, and reiterate the importance of accounting for technical, biological, and random error when examining heterogeneity in health-related training adaptations.Highlights This study tested whether true interindividual variability exists for changes in insulin sensitivity and glyceamic control following 6-weeks of low volume sprint interval training (SIT).The high level of technical, biological, and random error associated with repeated measurements of insulin sensitivity and glycaemic control, means we can neither confidently conclude that there is evidence of true interindividual differences in the trainability of these outcomes following SIT, nor confidently identify responders or non-responders for such parameters.Researchers contrasting responders vs. non-responders for a given parameter, either to understand mechanisms of adaptation and/or develop physiological/genetic/epigenetic predictors of response, need to be aware that identification of responders and non-responders with sufficient certainty may not be achievable for parameters with a high level of technical, biological, and random error.

Meta-analysis of variation in sport and exercise science: Examples of application within resistance training research

Meta-analysis has become commonplace within sport and exercise science for synthesising and summarising empirical studies. However, most research in the field focuses upon mean effects, particularly the effects of interventions to improve outcomes such as fitness or performance. It is thought that individual responses to interventions vary considerably. Hence, interest has increased in exploring precision or personalised exercise approaches. Not only is the mean often affected by interventions, but variation may also be impacted. Exploration of variation in studies such as randomised controlled trials (RCTs) can yield insight into interindividual heterogeneity in response to interventions and help determine generalisability of effects. Yet, larger samples sizes than those used for typical mean effects are required when probing variation. Thus, in a field with small samples such as sport and exercise science, exploration of variation through a meta-analytic framework is appealing. Despite the value of embracing and exploring variation alongside mean effects in sport and exercise science, it is rarely applied to research synthesis through meta-analysis. We introduce and evaluate different effect size calculations along with models for meta-analysis of variation using relatable examples from resistance training RCTs.

Inter-individual variability in redox and performance responses after antioxidant supplementation: A randomized double blind crossover study

AIM

We aimed to investigate the inter-individual variability in redox and physiological responses of antioxidant-deficient subjects after antioxidant supplementation.

METHODS

Two hundred individuals were sorted by plasma vitamin C levels. A low vitamin C group (n = 22) and a control group (n = 22) were compared in terms of oxidative stress and performance. Subsequently, the low vitamin C group received for 30 days vitamin C (1 g) or placebo, in randomized, double-blind, crossover fashion, and the effects were examined through a mixed-effects model, while individual responses were calculated.

RESULTS

The low vitamin C group exhibited lower vitamin C (-25 μmol/L; 95%CI[-31.7, -18.3]; p < 0.001), higher F2 -isoprostanes (+17.1 pg/mL; 95%CI[6.5, 27.7]; p = 0.002), impaired VO2max (-8.2 mL/kg/min; 95%CI[-12.8, -3.6]; p < 0.001) and lower isometric peak torque (-41.5 Nm; 95%CI[-61.8, -21.2]; p < 0.001) compared to the control group. Regarding antioxidant supplementation, a significant treatment effect was found in vitamin C (+11.6 μmol/L; 95%CI[6.8, 17.1], p < 0.001), F2 -isoprostanes (-13.7 pg/mL; 95%CI[-18.9, -8.4], p < 0.001), VO2max (+5.4 mL/kg/min; 95%CI[2.7, 8.2], p = 0.001) and isometric peak torque (+18.7; 95%CI[11.8, 25.7 Nm], p < 0.001). The standard deviation for individual responses (SDir) was greater than the smallest worthwhile change (SWC) for all variables indicating meaningful inter-individual variability. When a minimal clinically important difference (MCID) was set, inter-individual variability remained for VO2max , but not for isometric peak torque.

CONCLUSION

The proportion of response was generally high after supplementation (82.9%-95.3%); however, a few participants did not benefit from the treatment. This underlines the potential need for personalized nutritional interventions in an exercise physiology context.

Blood-Based Biomarkers for Managing Workload in Athletes: Considerations and Recommendations for Evidence-Based Use of Established Biomarkers

Blood-based biomarkers can provide an objective individualized measure of training load, recovery, and health status in order to reduce injury risk and maximize performance. Despite enormous potentials, especially owing to currently evolving technology, such as point-of-care testing, and advantages, in terms of objectivity and non-interference with the training process, there are several pitfalls in the use and interpretation of biomarkers. Confounding variables such as preanalytical conditions, inter-individual differences, or an individual chronic workload can lead to variance in resting levels. In addition, statistical considerations such as the detection of meaningful minimal changes are often neglected. The lack of generally applicable and individual reference levels further complicates the interpretation of level changes and thus load management via biomarkers. Here, the potentials and pitfalls of blood-based biomarkers are described, followed by an overview of established biomarkers currently used to support workload management. Creatine kinase is discussed in terms of its evidence for workload management to illustrate the limited applicability of established markers for workload management to date. We conclude with recommendations for best practices in the use and interpretation of biomarkers in a sport-specific context.

The Prevalence of Responders and Non-Responders for Body Composition, Resting Blood Pressure, Musculoskeletal, and Cardiorespiratory Fitness after Ten Weeks of School-Based High-Intensity Interval Training in Adolescents

Many observations have demonstrated great heterogeneity in the magnitude of the response to the physical exercise stimulus. Only a few studies have investigated the effects of high-intensity interval training (HIIT) on the prevalence of non-responders (NRs) in adolescents while considering health-related fitness measurements and other co-variables. Therefore, the aim of the current work was twofold: (1) to assess the effects of ten weeks of school-based HIIT on the prevalence of responders (Rs) and NRs for body composition, resting blood pressure (BP), cardiorespiratory and musculoskeletal fitness, and (2) to assess the relationship of this prevalence with sex, body mass category, and biological maturation status, while estimating the likelihood of a response. Adolescents aged 16 years (n = 73) were included in the study. Waist-to-hip ratio, body fat percentage (BFP), skeletal muscle mass (SMM), BP, cardiorespiratory fitness (CRF), and musculoskeletal fitness were the primary outcomes. Co-variables included sex, body mass index (BMI), and maturity offset. The percentages of the Rs and NRs were analyzed based on changes (Δ) between post-intervention and pre-intervention values. The typical error (TE) method was used to identify Rs and NRs. Results showed a variation in the relative size of changes (% of changes) depending on the variable and sex. The greatest changes were observed in females' abdomen muscle strength (Δ% = 23.89%), and the difference from that of males (Δ% = 5.98%) was statistically significant (p < 0.001) with very large effect size of (Cohen's d = 0.941). Similar significant differences in relative changes were observed in body composition, but in the reverse direction. Males gained more from HIIT in the decrease in the body fat percentage (Δ% = -8.24%) and increase in skeletal muscle mass (Δ% = 3.38%) comparing to females (Δ% = 0.46, p = 0.040 and Δ% = 1.06%, p = 0.007, respectively). Effect size for body fat was small (Cohen's d = 0.469), and for skeletal muscle mass it was moderate (Cohen's d = -0.659). The results also showed positive significant differences in the prevalence of Rs compared to NRs in BFP, SMM, systolic BP (SBP), diastolic BP (DBP), CRF, and abdominal muscular strength (ABS) (p = 0.047, p = 0.047, p < 0.001, p = 0.003, p = 0.014, and p = 0.014, respectively). The effect was greatest and largest for SBP (Cohen's ω = 0.67). Sex was related to the prevalence of Rs for ABS and close to significance for SMM. More males than females benefited from HIIT in SMM (p = 0.058), but more females than males had ABS benefits (p = 0.050). Males were more likely (2.5-fold) to be Rs than females in SMM. BMI was not related to the prevalence of Rs and NRs. Biological maturation was related to the prevalence of Rs and NRs in SMM (p = 0.036) and SBP (p = 0.016). In SBP, 100% of the early matured derived benefit from HIIT, but the effect size was small (Cramer's V = 0.27). Those who maturated later were more likely (almost 70%) to be Rs. Thus, the HIIT program introduced to a typical physical education (PE) lesson can be considered partially effective. Therefore, there is a need to continue the search for an optimal and effective program for all health-related parameters. The close relationship between analyzed values and sex and biological maturation, but not BMI, indicates that the intervention programs should be tailored specifically for males and females.

Evaluating individual level change in physical function response following an exercise program for cancer survivors

PURPOSE

Cancer survivors physical function response to exercise programs at the group level is well-established. However, to advance toward a more personalized approach in exercise oncology, a greater understanding of individual response is needed. This study utilized data from a well-established cancer-exercise program to evaluate the heterogeneity of physical function response and explore characteristics of participants who did vs. did not achieve a minimal clinically important difference (MCID).

METHODS

Physical function measures (grip strength, 6-min walk test (6MWT), and sit-to-stand) were completed pre/post the 3-month program. Change scores for each participant and the proportion achieving the MCID for each physical function measure were calculated. The independent t-tests, Fisher's exact test, and decision tree analyses were used to explore differences in age, body mass index (BMI), treatment status, exercise session attendance, and baseline value between participants who achieved the MCID vs. those who did not.

RESULTS

Participants (N = 250) were 55 ± 14 years old, majority female (69.2%), white (84.1%), and diagnosed with breast cancer (36.8%). Change in grip strength ranged from - 42.1 to + 47.0 lb, and 14.8% achieved the MCID. Change in 6MWT ranged from - 151 to + 252 m, and 59% achieved the MCID. Change in sit-to-stand ranged from - 13 to + 20 reps, and 63% achieved the MCID. Baseline grip strength, age, BMI, and exercise session attendance were related to achieving MCID.

CONCLUSIONS

Findings illustrate wide variability in the magnitude of cancer survivors' physical function response following an exercise program, and that a variety of factors predict response. Further investigation into the biological, behavioral, physiological, and genetic factors will inform tailoring of exercise interventions and programs to maximize the proportion of cancer survivors who can derive clinically meaningful benefits.

Effects of resistance training on body weight and body composition in older adults: An inter-individual response difference meta-analysis of randomized controlled trials

Whether true inter-individual response differences (IIRD) occur as a result of resistance training on body weight and body composition in older adults with overweight and obesity is not known. To address this gap, data from a previous meta-analysis representing 587 men and women (333 resistance training, 254 control) ≥ 60 years of age nested in 15 randomized controlled trials of resistance training ≥ 8 weeks were included. Resistance training and control group change outcome standard deviations treated as point estimates for body weight and body composition (percent body fat, fat mass, body mass index in kg.m2, and lean body mass) were used to calculate true IIRD from each study. True IIRD as well as traditional pairwise comparisons were pooled using the inverse-variance (IVhet) model. Both 95% confidence intervals (CI) and prediction intervals (PI) were calculated. While statistically significant improvements were found for body weight and all body composition outcomes (p < 0.05 for all), no statistically significant IIRD was observed for any of the outcomes (p > 0.05 for all) and all 95% PIs overlapped. Conclusions: While resistance training is associated with improvements in body weight and body composition in older adults, the lack of true IIRD suggests that factors other than training response variation (random variation, physiological responses associated with behavioral changes that are not the result of resistance training) are responsible for the observed variation in body weight and body composition.

Unsupervised cluster analysis reveals distinct subgroups in healthy population with different exercise responses of cardiorespiratory fitness

Background

Considerable attention has been paid to interindividual differences in the cardiorespiratory fitness (CRF) response to exercise. However, the complex multifactorial nature of CRF response variability poses a significant challenge to our understanding of this issue. We aimed to explore whether unsupervised clustering can take advantage of large amounts of clinical data and identify latent subgroups with different CRF exercise responses within a healthy population.

Methods

252 healthy participants (99 men, 153 women; 36.8 ± 13.4 yr) completed moderate endurance training on 3 days/week for 4 months, with exercise intensity prescribed based on anaerobic threshold (AT). Detailed clinical measures, including resting vital signs, ECG, cardiorespiratory parameters, echocardiography, heart rate variability, spirometry and laboratory data, were obtained before and after the exercise intervention. Baseline phenotypic variables that were significantly correlated with CRF exercise response were identified and subjected to selection steps, leaving 10 minimally redundant variables, including age, BMI, maximal oxygen uptake (VO_2max), maximal heart rate, VO₂ at AT as a percentage of VO_2max, minute ventilation at AT, interventricular septal thickness of end-systole, E velocity, root mean square of heart rate variability, and hematocrit. Agglomerative hierarchical clustering was performed on these variables to detect latent subgroups that may be associated with different CRF exercise responses.

Results

Unsupervised clustering revealed two mutually exclusive groups with distinct baseline phenotypes and CRF exercise responses. The two groups differed markedly in baseline characteristics, initial fitness, echocardiographic measurements, laboratory values, and heart rate variability parameters. A significant improvement in CRF following the 16-week endurance training, expressed by the absolute change in VO_2max, was observed only in one of the two groups (3.42 ± 0.4 vs 0.58 ± 0.65 ml⋅kg^-1∙min^-1, P = 0.002). Assuming a minimal clinically important difference of 3.5 ml⋅kg^-1∙min^-1 in VO_2max, the proportion of population response was 56.1% and 13.9% for group 1 and group 2, respectively (P<0.001). Although group 1 exhibited no significant improvement in CRF at group level, a significant decrease in diastolic blood pressure (70.4 ± 7.8 vs 68.7 ± 7.2 mm Hg, P = 0.027) was observed.

Conclusions

Unsupervised learning based on dense phenotypic characteristics identified meaningful subgroups within a healthy population with different CRF responses following standardized aerobic training. Our model could serve as a useful tool for clinicians to develop personalized exercise prescriptions and optimize training effects.

Fractal correlation properties of HRV as a noninvasive biomarker to assess the physiological status of triathletes during simulated warm-up sessions at low exercise intensity: a pilot study

BACKGROUND

The non-linear index alpha 1 of Detrended Fluctuation Analysis (DFA a1) of heart rate variability, has been shown to be a marker of fatigue during endurance exercise. This report aims to explore its ability to assess the physiological status as a surrogate metric for "readiness to train" while performing simulated warm-up sessions the day after two different exercise sessions.

METHODS

11 triathletes were recruited to determine the first ventilatory threshold (VT1) during a baseline assessment and to perform 10-min of cycling at 90% of VT1 (simulating a warm-up bout) before (PRE) and within 36 h after (POST) light and heavy running exercise. RR intervals were recorded for DFA a1 analysis along with neuromuscular testing to verify the effects of the performed exercise sessions. In addition to common statistical methods, magnitude-based inferences (MBI) were applied to assess the changes in true score and thus also the practical relevance of the magnitude.

RESULTS

Rating of perceived exertion for the heavy exercise session showed a significant higher rating as opposed to the light exercise session (p < 0.001, d = 0.89). In regard of MBIs, PRE versus POST comparisons revealed a significant reduced DFA a1 with large effect size after the heavy exercise session (p = 0.001, d = - 1.44) and a 99% chance that this negative change was clinically relevant.

CONCLUSIONS

Despite inter-individual differences, DFA a1 offers potential to assess physiological status and guide athletes in their training as an easy-to-apply monitoring procedure during a standardized warm-up. A regular assessment including individual data history and statistical references for identification of response is recommended. Further data are necessary to confirm the results in a larger and more homogeneous population.

Interindividual variability in metabolic adaptation of non-exercise activity thermogenesis after a 1-year weight loss intervention in former elite athletes

Lack of efficacy of weight loss(WL) interventions is attributed in-part to low adherence to dietary/physical activity(PA) recommendations. However, some compensation may occur in PA as a response to energy restriction such as a decrease in non-exercise PA(NEPA) or non-exercise activity thermogenesis(NEAT). The current study aim was (1) to investigate whether adaptive thermogenesis(AT) in NEAT occurs after WL, and (2) to understand the associations of these compensations with WL. Ninety-four former athletes [mean±SD, age: 43.0±9.4y, BMI: 31.1±4.3 kg/m², 34.0% female] were recruited and randomly assigned to intervention or control groups (IG, CG). The IG underwent a one-year lifestyle WL-intervention; no treatments were administered to the CG. PA was measured using accelerometery and NEAT was predicted with a model including sample baseline characteristics. AT was calculated as _measuredNEAT^4mo/12mo_(kcal/d)-_predictedNEAT^4mo/12mo_(kcal/d)-_measuredNEAT^baseline_(kcal/d)-_predictedNEAT^baseline_(kcal/d). Dual-energy x-ray absorptiometry was used to assess fat-free mass and fat mass. No differences were found in the IG for NEAT or NEPA after WL. Considering mean values, AT was not found for either group. The SD of individual response (SD_IR) for AT was -2(4-months) and 24(12-months) (smallest worthwhile change = 87kcal/d), suggesting that the interindividual variability regarding AT in NEAT is not relevant and the variability in this outcome might reflect a large within-subject variability and/or a large degree of random measurement error. No associations were found between AT in NEAT and changes in body composition. Further studies are needed to clarify the mechanisms behind the large variability in AT observed in NEAT and related changes in NEPA to better implement lifestyle-induced WL interventions.Highlights No significant differences were found for non-exercise activity thermogenesis (NEAT) or non-exercise physical activity (NEPA) after the weight loss (WL) intervention;Although a large variability was found for NEAT and NEPA, the interindividual variability regarding these outcomes is not relevant. The variability in these outcomes might reflect a large within-subject variability and/or a large degree of random measurement error;Although no energy conservation was observed in NEAT after moderate WL (mean values), further studies are needed to clarify the mechanisms behind the large variability in adaptive thermogenesis observed in NEAT and related changes in NEPA to better implement lifestyle-induced WL interventions.Trial registration: ClinicalTrials.gov identifier: NCT03031951.

Models predict change in plasma triglyceride concentrations and long-chain n-3 polyunsaturated fatty acid proportions in healthy participants after fish oil intervention

Introduction

Substantial response heterogeneity is commonly seen in dietary intervention trials. In larger datasets, this variability can be exploited to identify predictors, for example genetic and/or phenotypic baseline characteristics, associated with response in an outcome of interest.

Objective

Using data from a placebo-controlled crossover study (the FINGEN study), supplementing with two doses of long chain n-3 polyunsaturated fatty acids (LC n-3 PUFAs), the primary goal of this analysis was to develop models to predict change in concentrations of plasma triglycerides (TG), and in the plasma phosphatidylcholine (PC) LC n-3 PUFAs eicosapentaenoic acid (EPA) + docosahexaenoic acid (DHA), after fish oil (FO) supplementation. A secondary goal was to establish if clustering of data prior to FO supplementation would lead to identification of groups of participants who responded differentially.

Methods

To generate models for the outcomes of interest, variable selection methods (forward and backward stepwise selection, LASSO and the Boruta algorithm) were applied to identify suitable predictors. The final model was chosen based on the lowest validation set root mean squared error (RMSE) after applying each method across multiple imputed datasets. Unsupervised clustering of data prior to FO supplementation was implemented using k-medoids and hierarchical clustering, with cluster membership compared with changes in plasma TG and plasma PC EPA + DHA.

Results

Models for predicting response showed a greater TG-lowering after 1.8 g/day EPA + DHA with lower pre-intervention levels of plasma insulin, LDL cholesterol, C20:3n-6 and saturated fat consumption, but higher pre-intervention levels of plasma TG, and serum IL-10 and VCAM-1. Models also showed greater increases in plasma PC EPA + DHA with age and female sex. There were no statistically significant differences in PC EPA + DHA and TG responses between baseline clusters.

Conclusion

Our models established new predictors of response in TG (plasma insulin, LDL cholesterol, C20:3n-6, saturated fat consumption, TG, IL-10 and VCAM-1) and in PC EPA + DHA (age and sex) upon intervention with fish oil. We demonstrate how application of statistical methods can provide new insights for precision nutrition, by predicting participants who are most likely to respond beneficially to nutritional interventions.

Positive Effects of Pre-exercise Metabolic Alkalosis on Perceived Exertion and Post-exercise Squat Jump Performance in World-Class Cyclists

ABSTRACT

Thomas, C, Delfour-Peyrethon, R, Dorel, S, and Hanon, C. Positive effects of pre-exercise metabolic alkalosis on perceived exertion and post-exercise squat jump performance in world-class cyclists. J Strength Cond Res 36(9): 2602-2609, 2022-This study aimed to determine the effects of pre-exercise alkalosis in world-class cyclists on their general (rate of perceived exertion [RPE]) and local (category-ratio scale [CR10]) perceived rates of exertion and acid-base status during 2 types of training sessions. Eight world-class cyclists ingested either sodium bicarbonate (BIC) or a placebo (PLA) in a double-blind and randomized order before performing 4 × 1,000 m constant-power sprints (CP) or 3 × 500 m all-out sprints (AO), with 20 minutes of recovery time between each session. For AO, the performance was assessed through the cycling sprint velocity and a squat jump test during recovery. During both tests, RPE, CR10, and acid-base status were measured. Sodium bicarbonate ingestion was effective in inducing pre-exercise alkalosis, compared with a PLA ( p < 0.05). During CP, performance and RPE were the same for BIC and PLA ( p > 0.05) with no time effect. The CR10 increased for the last sprint in PLA ( p < 0.05) but was attenuated in BIC (BIC: 6 vs. PLA: 8.2; p < 0.05), whereas there was no difference in acid-base status. During AO, RPE and CR10 increased with time, with no BIC effect, whereas blood lactate concentration was different ( p < 0.05). Sodium bicarbonate supplementation had no effect on overall repeated sprints ( p > 0.05). However, world-class athletes responded to BIC with higher squat jump performance than the PLA condition after AO ( p < 0.05). Our results suggest a positive influence of pre-exercise alkalosis in world-class cyclists on local perception of efforts after constant load sprints and an attenuation of muscle power output decline postsprint, as evidenced by improved squat jump performance after all-out cycling effort.

Are There Interindividual Differences in Anxiety as a Result of Aerobic Exercise Training in Adults With Fibromyalgia? An Ancillary Meta-analysis of Randomized Controlled Trials

OBJECTIVE

To determine whether true interindividual response differences (IIRD) exist with respect to changes in anxiety because of aerobic exercise training in adults with fibromyalgia (FM).

DATA SOURCES

Data from a previous meta-analytical database of randomized controlled trials of exercise in adults with arthritis and other rheumatic diseases.

STUDY SELECTION

Randomized controlled trials limited to aerobic exercise training on anxiety in adults 18 years or older with FM were included.

DATA EXTRACTION

Change outcome SDs treated as point estimates for anxiety were used to calculate true IIRD from each study. In addition, treatment effect data were extracted.

DATA SYNTHESIS

The inverse variance heterogeneity model was used to pool all results. For the 5 studies and 321 participants in which results were pooled, statistically significant treatment effect reductions in anxiety were observed (mean, -0.77 points, 95% CI, -1.25 to -0.77). However, no significant IIRD were found (mean, 0.6 points, 95% CI, -1.2 to 1.5). The 95% prediction interval for true IIRD in a future study was -1.7 to 0.8. The percent chance, ie, probability, of a clinically meaningful difference in variability, was 61.5% (only possibly clinically important).

CONCLUSIONS

The results of the current study suggest that aerobic exercise is associated with reductions in anxiety among adults with fibromyalgia. However, there is currently a lack of convincing evidence to support the notion that true IIRD exist. Therefore, a search for potential mediators and moderators associated with aerobic exercise and changes in anxiety among adults with FM may not be warranted. However, additional research is needed before any true level of certainty can be established. This includes (1) the assessment of IIRD in future randomized controlled trials, (2) randomized controlled trials of longer duration, and (3) an increase in the proportion of men included in randomized controlled trials.

A combination of cherry juice and cold water immersion does not enhance marathon recovery compared to either treatment in isolation: A randomized placebo-controlled trial

Purpose

Cherry juice (CJ) and cold water immersion (CWI) are both effective recovery strategies following strenuous endurance exercise. However, athletes routinely combine recovery interventions and less is known about the impact of a combined CJ and CWI protocol. Therefore, this study investigated the effects of combining CWI and CJ (a “cocktail” (CT)) on inflammation and muscle damage following a marathon.

Methods

A total 39 endurance trained males were randomly assigned to a placebo (PL), CWI, CJ, or CT group before completing a trail marathon run. Muscle damage (creatine kinase (CK)), muscle function (maximal voluntary isometric contraction (MVIC)), and inflammation (interleukin-6 (IL-6); C-reactive protein (CRP)) were measured at baseline, immediately after marathon (only IL-6), 24 h, and 48 h after marathon.

Results

There were no statistically significant differences between groups and no group × time interaction effects for any of the dependent variables. Confidence intervals (CI) illustrated that CT had unclear effects on inflammation (IL-6; CRP) and MVIC, but may have increased CK to a greater extent than PL and CJ conditions.

Conclusion

There is no evidence of an additive effect of CJ and CWI when the treatments are used in conjunction with each other. On the contrary, combining CJ and CWI may result in slightly increased circulating CK.

Effects of a 4-month active weight loss phase followed by weight loss maintenance on adaptive thermogenesis in resting energy expenditure in former elite athletes

PURPOSE

Despite adaptive thermogenesis (AT) being studied as a barrier to weight loss (WL), few studies assessed AT in the resting energy expenditure (REE) compartment after WL maintenance. The aim of this study was twofold: (1) to understand if AT occurs after a moderate WL and if AT persists after a period of WL maintenance; and (2) if AT is associated with changes in body composition, hormones and energy intake (EI).

METHODS

Ninety-four participants [mean (SD); BMI, 31.1(4.3)kg/m²; 43.0(9.4)y; 34% female] were randomized to intervention (IG, n = 49) or control groups (CG, n = 45). Subjects underwent a 1-year lifestyle intervention, divided in 4 months of an active WL followed by 8 months of WL maintenance. Fat mass (FM) and fat-free mass (FFM) were measured by dual-energy X-ray absorptiometry and REE by indirect calorimetry. Predicted REE (pREE) was estimated through a model using FM, FFM. EI was measured by the "intake-balance" method.

RESULTS

For the IG, the weight and FM losses were - 4.8 (4.9) and - 11.3 (10.8)%, respectively (p < 0.001). A time-group interaction was found between groups for AT. After WL, the IG showed an AT of -85(29) kcal.d^-1 (p < 0.001), and remained significant after 1 year [AT = - 72(31)kcal.d^-1, p = 0.031]. Participants with higher degrees of restriction were those with an increased energy conservation (R = - 0.325, p = 0.036 and R = - 0.308, p = 0.047, respectively). No associations were found between diet adherence and AT. Following a sub-analysis in the IG, the group with a higher energy conservation showed a lower WL and fat loss and a higher initial EI.

CONCLUSION

AT in REE occurred after a moderate WL and remained significant after WL maintenance. More studies are needed to better clarify the mechanisms underlying the large variability observed in AT and providing an accurate methodological approach to avoid overstatements. Future studies on AT should consider not only changes in FM and FFM but also the FFM composition.

Inter-individual variations in response to aerobic and resistance training in hypertensive older adults

BACKGROUND

Hemodynamic responses to physical training are not homogenous and uniform, and considerable inter-individual variations in the blood pressure of hypertensive individuals are noted in both aerobic and resistance training protocols. In this context, this study aimed to evaluate the effects of resistance and aerobic exercise on the blood pressure responses of hypertensive older adults.

METHODS

Groups were randomly divided into resistance training, n = 20; aerobic training, n = 20; control group, n = 21). After the first intervention period (12 weeks), individuals underwent a washout period (six detraining weeks), followed by a second intervention. This process is called the 'cross-over' model, where individuals who performed the aerobic exercise protocol also performed resistance training and vice-versa, constituting another 12 weeks of intervention. Blood pressure, functional performance, glycated hemoglobin and lipid profiles were evaluated preintervention and postintervention.

RESULTS

Varying responses to resistance training or aerobic training stimuli were observed in the hypertensive older adult participants. Both resistance training (pre 133.2 ± 14.1; post 122.4 ± 7.3; P < 0.05) and aerobic training (pre 134.2 ± 14.4; post 123 ± 9.4; P < 0.0.5) were effective in decreasing SBP, but only aerobic training (pre 9955.3 ± 1769.4; post 8800.9 ± 1316.1; P < 0.05) resulted in a decreased double product, and only the resistance training group improved functional performance.

CONCLUSION

Responses to resistance training or aerobic training stimuli varied noticeably between hypertensive older adults and both resistance training and aerobic training were effective in reducing SBP. This knowledge may be useful in providing individually tailored exercise prescriptions for hypertensive older adults.

Effects of Aerobic Walking on Memory, Subjective Cognitive Complaints, and Brain-Derived Neurotrophic Factor Among Older Hypertensive Women

Background:Hypertension is prevalent in older women and is associated with increased cognitive impairment. Exercise has demonstrated beneficial effects on cognitive function, but the impact of exercise on older hypertensive women remains unclear. We investigated the effects of an aerobic walking program on memory, subjective cognitive complaints, and brain-derived neurotrophic factor in older hypertensive women. Methods: A quasi-experimental study with a pretest-posttest design was conducted. Older hypertensive women were randomly assigned to the aerobic walking group or a control group with routine care. The intervention group received a 24-week aerobic walking program. Data were collected at baseline and 24 weeks after enrollment. Participants' characteristics, memory, subjective cognitive complaints, and plasma brain-derived neurotrophic factor were analyzed. Results: The aerobic walking group (n = 30) reported improvements in total recall, delayed recall, and subjective cognitive impairment after 24 weeks of aerobic walking. Compared to the control group (n = 28), the aerobic walking group showed significantly greater improvement in delayed recall at 24 weeks. However, aerobic walking had no significant effect on subjective cognitive complaints or brain-derived neurotrophic factor. Conclusion: The aerobic walking training significantly improved memory performance among older women with hypertension. A longer randomized controlled trial with a larger sample is necessary to confirm and further explore the effects of this intervention.

An Examination of Two Resistance Training Frequency Techniques in Morphological and Functional Adaptations of the Patellar Tendon

The aim of the present study was to investigate the effects of distinct resistance training frequencies with equated-volume conditions in morphological and functional adaptations of the patellar tendon. Twenty-seven recreationally resistance-trained subjects (men [n=17] and women [n=10]) (age: 20.8 ± 1.9 years [range 18 to 25 years]; height: 1.73 ± 9.8 cm; total body mass = 73.2 ± 11.7 kg; previous RT experience = 3.3 ± 1.6 years) volunteered to participate in this study. A total of 16 training sessions were performed during the study period. Each subject's leg was randomly allocated to one of the following training protocols: 2 training sessions/week (2x) or 4 training sessions/week (4x). Measurements of tendon cross sectional area (CSA) and length were performed through ultrasound imaging. One repetition maximum test was performed to assess patellar tendon force (PTF) unilaterally. For CSA (2x: Δ= -1.3%; 4x: Δ= -0.9%), and length (2x: Δ= -0.4%; 4x: Δ= 1.2%), no significant differences were observed within or between conditions (all p > 0.05). For PTF, a significant difference was observed between conditions (mean difference = 0.05 [-125 to 224] p= 0.001). In conclusion, the leg extension exercise performed 2 vs 4x/week induces similar patellar tendon morphological responses. However, the increase in force seems to be enhanced by a lower weekly training frequency associated with a longer intervention period.

Multitask Versus Multicomponent Training on Cognitive and Motor Functions in Persons With Mild Cognitive Impairment: A Randomized Trial

This study aims to compare the effects of multitask (MTT; multiple tasks performed simultaneously) and multicomponent training (MCT; various types of exercise performed sequentially) on processing speed, cognitive functions, gait speed, and balance functions in persons with mild cognitive impairment. Forty-two persons with mild cognitive impairment were randomly allocated to MTT (n = 21) or MCT (n = 21). Outcome measures included processing speed, cognitive functions (attention and executive functions), single-task gait speed, dual-task gait speed (DTGS-Arithmetic and DTGS-Verbal), and balance functions. Processing speed (except inhibition), cognitive functions, gait speed, and balance functions improved in the MTT and MCT groups following training, with no significant differences between the groups in processing speed or cognitive functions. The MCT group improved more on single-task gait speed (F = 15.097; p = .000; r = .270) and DTGS (DTGS-Arithmetic; F = 10.594; p = .002; r = .214), while the MTT group improved more on balance functions (F = 4.366; p = .043; r = .101). MTT and MCT strategies can be used to improve cognitive and physical outcomes in persons with mild cognitive impairment.

Interindividual variability in response to protein and fish oil supplementation in older adults: a randomized controlled trial

BACKGROUND

Precision nutrition is highly topical. However, no studies have explored the interindividual variability in response to nutrition interventions for sarcopenia. The purpose of this study was to determine the magnitude of interindividual variability in response to two nutrition supplementation interventions for sarcopenia and metabolic health, after accounting for sources of variability not attributable to supplementation.

METHODS

A 24 week, randomized, double-blind, placebo-controlled trial tested the impact of leucine-enriched protein (LEU-PRO), LEU-PRO plus long-chain n-3 PUFA (LEU-PRO+n-3) or control (CON) supplementation in older adults (n = 83, 71 ± 6 years) at risk of sarcopenia. To estimate the true interindividual variability in response to supplementation (free of the variability due to measurement error and within-subject variation), the standard deviation of individual responses (SD_R ) was computed and compared with the minimally clinically important difference (MCID) for appendicular lean mass (ALM), leg strength, timed up-and-go (TUG), and serum triacylglycerol (TG) concentration. Clinically meaningful interindividual variability in response to supplementation was deemed to be present when the SD_R positively exceeded the MCID. The probability that individual responses were clinically meaningful, and the phenotypic, dietary, and behavioural determinants of response to supplementation were examined.

RESULTS

The SD_R was below the MCID for ALM (LEU-PRO: -0.12 kg [90% CI: -0.38, 0.35], LEU-PRO+n-3: -0.32 kg [-0.45, 0.03], MCID: 0.21 kg), TUG (LEU-PRO: 0.58 s [0.18, 0.80], LEU-PRO+n-3: 0.73 s [0.41, 0.95], MCID: 0.9 s) and TG (LEU-PRO: -0.38 mmol/L [-0.80, 0.25], LEU-PRO+n-3: -0.44 mmol/L [-0.63, 0.06], MCID: 0.1 mmol/L), indicating no meaningful interindividual variability in response to either supplement. The SD_R exceeded the MCID (19 Nm) for strength in response to LEU-PRO (25 Nm [-29, 45]) and LEU-PRO+n-3 (23 Nm [-29, 43]) supplementation but the effect was uncertain, evidenced by wide confidence intervals. In the next stage of analysis, similar proportions of participant responses were identified as very likely, likely, possibly, unlikely, and very unlikely to represent clinically meaningful improvements across the LEU-PRO, LEU-PRO+n-3, and CON groups (P > 0.05). Baseline LC n-3 PUFA status, habitual protein intake, and numerous other phenotypic and behavioural factors were not determinants of response to LEU-PRO or LEU-PRO+n-3 supplementation.

CONCLUSIONS

Applying a novel, robust methodological approach to precision nutrition, we show that there was minimal interindividual variability in changes in ALM, muscle function, and TG in response to LEU-PRO and LEU-PRO+n-3 supplementation in older adults at risk of sarcopenia.

Walking and resting blood pressure: An inter-individual response difference meta-analysis of randomized controlled trials

While walking is associated with reductions in resting SBP and DBP, a lack of true IIRD exists, suggesting that factors other than training response variation (random variation, physiological responses associated with behavioral changes that are not the result of walking) are responsible for the observed variation in resting SBP and DBP.

Initial Muscle Quality Affects Individual Responsiveness of Interleukin-6 and Creatine Kinase following Acute Eccentric Exercise in Sedentary Obese Older Women

This study aimed to evaluate the time course and responsiveness of plasma interleukin-6 (IL-6) and creatine kinase (CK) levels following acute eccentric resistance exercise in sedentary obese older women with a different muscle quality index (MQI). Eighty-eight participants (69.4 ± 6.06 years) completed an acute eccentric resistance exercise (7 sets of 10 repetitions at 110% of 10-repetition maximum with 3 min rest interval). Participants were divided into two groups: high or low MQI according to 50th percentile cut-off. The responsiveness was based on minimal clinical important difference. There were no differences between groups and time on IL-6 and CK levels (p > 0.05). However, the high MQI group displayed a lower proportion of low responders (1 for laboratory and 2 for field-based vs. 5 and 4) and a higher proportion of high responders for IL-6 (7 for laboratory and 6 for field-based vs. 4 and 5) compared to low MQI group. In addition, the high MQI group showed a higher proportion of high responders for CK (11 for laboratory and 9 for field-based vs. 6 and 6) compared to low MQI. A prior MQI screening can provide feedback to understand the magnitude response. Individual responsiveness should be taken into consideration for maximizing eccentric exercise prescription.

Anthocyanin-Rich Supplementation: Emerging Evidence of Strong Potential for Sport and Exercise Nutrition

Dark-colored fruits, especially berries, have abundant presence of the polyphenol anthocyanin which have been show to provide health benefits. Studies with the berry blackcurrant have provided notable observations with application for athletes and physically active individuals. Alterations in exercise-induced substrate oxidation, exercise performance of repeated high-intensity running and cycling time-trial and cardiovascular function at rest and during exercise were observed with intake of New Zealand blackcurrant. The dynamic plasma bioavailability of the blackcurrant anthocyanins and the anthocyanin-derived metabolites must have changed cell function to provide meaningful in-vivo physiological effects. This perspective will reflect on the research studies for obtaining the applied in-vivo effects by intake of anthocyanin-rich supplementation, the issue of individual responses, and the emerging strong potential of anthocyanins for sport and exercise nutrition. Future work with repeated intake of known amount and type of anthocyanins, gut microbiota handling of anthocyanins, and coinciding measurements of plasma anthocyanin and anthocyanin-derived metabolites and in-vivo cell function will be required to inform our understanding for the unique potential of anthocyanins as a nutritional ergogenic aid for delivering meaningful effects for a wide range of athletes and physically active individuals.

Effects of 6-Month Square Stepping Exercise Intervention on Physical and Cognitive Competence, Regucalcin, and Body Composition in Older People: Study Protocol for a Randomised Control Trial

Background: Age-related changes negatively affect physical fitness, body composition, and executive function and produce a decrease in regucalcin level expression in blood. The square-stepping exercise (SSE) is a balance and lower-limb strength training programme used to prevent falls and stimulate cognitive function in older adults. This project aims to analyse the effects of SSE on executive function, regucalcin expression, fall prevention, body composition, and physical fitness in people over 65 years old. Methods: A randomized controlled trial will be conducted. A total of 90 older people over 65 years old will be recruited and randomly assigned to 2 groups: experimental (n = 45) and control (n = 45). The experimental group will perform an SSE-based intervention for 6 months (2 times per week), while the control group do not follow any treatment. Results: The main outcome will be balance, but other motor (body mass index, upper- and lower-limb strength, flexibility, and speed-agility) and cognitive variables (executive functions and attention) will be assessed. The expression of regucalcin levels will also be evaluated. Therefore, this project aims to analyse the effect of a 6-month SSE intervention on cognitive and motor competence, physical fitness, regucalcin levels, fall risk, and body composition in older people. If the intervention proves to be effective, it could be implemented in centres, entities, and associations specialized in elderly care.

Inter-individual Response Differences on Resting Blood Pressure as a Result of Qigong in Adults: An Ancillary Meta-Analysis of Randomized Trials

OBJECTIVE

Conduct an ancillary meta-analysis to determine whether true IIRD exist with respect to the effects of qigong on resting SBP and DBP in adults.

METHODS

Data from a meta-analysis representing 370 participants (181 qigong, 189 control) from 7 randomized trials on qigong and resting SBP and DBP in men and women were included. Qigong and control group change outcome standard deviations treated as point estimates for both resting SBP and DBP were used to calculate true IIRD from each study and the inverse variance heterogeneity (IVhet) model was used to pool results.

RESULTS

For participants with essential hypertension, statistically significant and clinically important reductions in resting SBP (X̅, -18.2mmHg, 95% CI, -21.3 to -15.2mmHg) and DBP (X̅, -11.7mmHg, 95% CI, -17.0 to -6.3mmHg) were found. However, true IIRD were neither significant or clinically important for either SBP (X̅, -6.0mmHg, 95% CI, -9.1 to 3.5mmHg) or DBP (X̅, 2.8mmHg, 95% CI, -3.4 to 5.2mmHg). The 95% prediction interval for true IIRD was -11.9 to 8.4mmHg for SBP and -5.8 to 7.0mmHg for DBP.

CONCLUSIONS

While qigong is associated with reductions in resting SBP and DBP in adults with essential hypertension, a lack of true IIRD exists, suggesting that other external factors are responsible for any variation.