Validity of the relative percent concept for equating training intensity

Exercise heart rates determined by a ventilatory threshold vs. standardized equation methods in individuals with metabolic syndrome

This study aimed to compare the target heart rate (THR) for aerobic exercise based on standardized physiological maximum value percentages with the first-ventilatory-threshold heart rate (HRVT1) in individuals with metabolic syndrome. Three HRmax prediction equations were used to calculate the THR as 35%, 40% and 45% of the heart rate reserve (HRR) and 55%, 60% and 65% of the HRmax, and the results were compared with the HRVT1. The HRVT1 was measured through a CPET that complied with current guidelines and laboratory standards. In addition, the THRs calculated by combining the HRmax-measured values with standardized methods were compared with those of HRVT1 as a supplement for situations where HRmax-measured values can be evaluated but gas exchange analysis cannot be performed. According to the Fox equation, the difference between the HRVT1 and 35% HRR was not statistically significant (t = - 0.528, P = 0.600). Bland‒Altman analysis indicated that the mean difference between the two values was - 0.350, which was close to the 0th line (SD: ± 4.595; 95% CI - 1.684-0.984), with 95% limits of agreement ranging from - 9.356 to 8.656; the interclass correlation coefficient (ICC) was 0.862 (P < 0.001, 95% CI 0.766-0.920), indicating high reliability. Regarding the results, the measured values indicate that 40% HRR and 70% HRPeak showed good reliability with HRVT1 (ICC: 0.850, 95% CI 0.747-0.913; and ICC: 0.719, 95% CI 0.551-0.832, respectively). Among Chinese patients with MetS, the THR calculated by combining the standardized 35% HRR method with the Fox equation shows excellent agreement with the HRVT1 obtained from the CPET. When the HRPeak can be obtained, the THR calculated from the 40% HRR and 70% HRPeak can better estimate the HRVT1. The above results can be used to guide patients to gradually start exercise training near the VT1 in cases where CPET data cannot be obtained.

Fitness and Mortality Outcomes Associated With Supramaximal Peak Heart Rate on Treadmill Exercise Stress Testing

Inability to reach age-predicted peak heart rate (APPHR) on treadmill exercise testing (TMET) is associated with lower fitness and increased mortality. The significance of a "supramaximal" heart rate (≥105% of APPHR) is poorly understood; as such, we sought to investigate this relationship. We queried the Mayo Stress database from 1993 to 2010 for patients >30 years old without cardiovascular disease and not on antichronotropic therapy. Patients were stratified into groups based on APPHR: <75%, 75% to 84%, 85% to 94%, 95% to 104%, and ≥105%, with 105% to 114% and ≥115% subgroups. Functional aerobic capacity (FAC) was assessed by ANOVA and all-cause mortality by cox hazard regression; we adjusted for confounders. In total, 18,961 patients were included; 1150 (6.1%) died. 2,144 (11.3%) of patients achieved submaximal APPHR (<85%), 2,917 achieved supramaximal APPHR (≥105%). Patients with submaximal APPHR had significantly lower FAC: 76.4% (p <0.0001) [<75%], 83.5% (p <0.0001) [≥75% to <85%]. Those with supramaximal APPHR had significantly higher FAC: 102.0% (p <0.0001). Patients with submaximal APPHR had significantly higher mortality risks: <75% (adjusted HR 2.36 [1.83 to 3.04], p <0.0001) and ≥75 to <85% (adjusted HR 1.93 [1.62 to 2.31], p <0.0001). Those with supramaximal APPHR, after adjustment for cardiac risk factors and resting heart rate, had significantly lower mortality risk (adjusted HR 0.83 [0.70 to 0.99], p = 0.0414). In conclusion, supramaximal heart rate on TMET was associated with significantly higher FAC and lower all-cause mortality risk.

Tailoring exercise intensity: Acute and chronic effects of constant-speed and heart rate-clamped exercise in healthy, inactive adults

OBJECTIVES

This study tested whether speed-controlled exercise prescriptions result in greater external training load and acute cardiorespiratory responses at the end of exercise compared to heart rate-controlled prescriptions, despite equivalent intensity at the start of exercise. It also investigated whether speed-controlled prescriptions lead to greater improvements in cardiorespiratory fitness after 8 weeks of training.

DESIGN

A two-group, randomized block design with repeated testing sessions.

METHODS

Thirty-four healthy, inactive adults were randomized into two groups. One group trained at a constant speed set midway between the first and second lactate thresholds, whereas the other trained at the corresponding heart rate. Both groups performed 30 min of continuous exercise three times per week for 8 weeks. Speed, heart rate, and oxygen consumption were measured at the end of the first session and later time points for complementary analysis. Peak treadmill speed and maximal oxygen consumption were assessed before and after the intervention.

RESULTS

At the end of the first session, the speed group showed higher values compared to the heart rate group for speed (1.5 km/h), heart rate (22 bpm), and oxygen consumption (6.0 mL/kg/min) (all p < 0.001). Similarly, adaptive changes were greater in the speed group, with a larger increase in peak treadmill speed (0.9 km/h, p < 0.001) and maximal oxygen consumption (1.2 mL/kg/min, p = 0.01).

CONCLUSIONS

These findings indicate that the exercise intensity reference method influences acute responses and chronic adaptations to exercise in healthy, inactive adults.

High-Intensity Interval Training for Cancer Patients: A Review of Key Considerations for Exercise Prescription

BACKGROUND

High-intensity interval training (HIIT) performed before, during, and after cancer treatment can attenuate the adverse effects induced by anti-cancer drugs. A clear presentation and rationale of characteristics of HIIT variables is vital to produce the expected HIIT adaptations in cancer patients. However, there are concerns regarding the HIIT protocols used in the cancer literature.

OBJECTIVES

The aims were to (1) identify the characteristics of HIIT and the formats that have been prescribed, (2) analyze which anchors have been utilized to prescribe effort and pause intensity, (3) examine characteristics of the physical tests used for HIIT prescription, and (4) identify potential adverse events related to HIIT intervention.

METHODS

This scoping review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR) guidelines, including PubMed, Scopus, and Web of Science databases.

RESULTS

A total of 51 studies were retrieved, and the following results were found: (1) Only 25 studies reported all four essential variables for HIIT prescription [effort intensity (effort duration): pause intensity (pause duration)]. Of these studies, 23 used active pause and employed the following prescription (on average): [84% (116 s): 39% (118 s)] when percentage of maximal aerobic power (MAP) [maximal/peak oxygen uptake ( V O2max/peak)/MAP] was used; [124% (161 s): 55% (142 s)] when percentage of anaerobic threshold (AT) was used; [83% (230 s): 62% (165 s)] when maximal heart rate percentage (%HRmax) was used. From these 23 studies, 12 used V O2max/peak/MAP (one of the most recommended variables for HIIT prescription). Seven studies adopted the HIIT-long format, and in the remaining five studies, the format was unclear. (2) Twenty-four studies used fractions of V O2max/peak or mechanical variables like MAP as anchors for prescribing effort intensity, two studies used AT, 20 studies used fractions of HRmax/heart rate reserve, two studies used rate of perceived exertion (RPE), while one used RPE and % V O2peak concomitantly, and two studies utilized RPE/%HRmax concomitantly. Two studies utilized passive resting, 12 studies used % V O2peak/%MAP for prescribing pause intensity, four studies used AT, seven studies used %HRmax, one study used %HRmax/% V O2peak, and two studies used absolute loads. (3) Ten studies did not report the characteristics of the physical tests employed, two studies used submaximal tests, and 39 studies utilized graded exercise tests. (4) Ten studies did not report if there were adverse events associated with the exercise program, while 34 studies did not report any adverse events.

CONCLUSIONS

Only 50% of the studies provided all the necessary variables for accurate HIIT prescription, raising concerns about the replicability, comprehension, and effective application of HIIT in cancer patients. Most of the studies that reported all variables appeared to have employed the HIIT-long format. Only a few studies used more individualized anchors (e.g., AT) to prescribe HIIT-long format for cancer patients, which is considered a very heterogeneous population.

Changes in Cardiorespiratory Fitness Following Exercise Training Prescribed Relative to Traditional Intensity Anchors and Physiological Thresholds: A Systematic Review with Meta-analysis of Individual Participant Data

BACKGROUND

It is unknown whether there are differences in maximal oxygen uptake ( V O2max) response when prescribing intensity relative to traditional (TRAD) anchors or to physiological thresholds (THR).

OBJECTIVES

The present meta-analysis sought to compare: (a) mean change in V O2max, (b) proportion of individuals increasing V O2max beyond a minimum important difference (MID) and (c) response variability in V O2max between TRAD and THR.

METHODS

Electronic databases were searched, yielding data for 1544 individuals from 42 studies. Two datasets were created, comprising studies with a control group ('controlled' studies), and without a control group ('non-controlled' studies). A Bayesian approach with multi-level distributional models was used to separately analyse V O2max change scores from the two datasets and inferences were made using Bayes factors (BF). The MID was predefined as one metabolic equivalent (MET; 3.5 mL kg-1 min-1).

RESULTS

In controlled studies, mean V O2max change was greater in the THR group compared with TRAD (4.1 versus 1.8 mL kg-1 min-1, BF > 100), with 64% of individuals in the THR group experiencing an increase in V O2max > MID, compared with 16% of individuals taking part in TRAD. Evidence indicated no difference in standard deviation of change between THR and TRAD (1.5 versus 1.7 mL kg-1 min-1, BF = 0.55), and greater variation in exercise groups relative to non-exercising controls (1.9 versus 1.3 mL kg-1 min-1, BF = 12.4). In non-controlled studies, mean V O2max change was greater in the THR group versus the TRAD group (4.4 versus 3.4 mL kg-1 min-1, BF = 35.1), with no difference in standard deviation of change (3.0 versus 3.2 mL kg-1 min-1, BF = 0.41).

CONCLUSION

Prescribing exercise intensity using THR approaches elicited superior mean changes in V O2max and increased the likelihood of increasing V O2max beyond the MID compared with TRAD. Researchers designing future exercise training studies should thus consider the use of THR approaches to prescribe exercise intensity where possible. Analysis comparing interventions with controls suggested the existence of intervention response heterogeneity; however, evidence was not obtained for a difference in response variability between THR and TRAD. Future primary research should be conducted with adequate power to investigate the scope of inter-individual differences in V O2max trainability, and if meaningful, the causative factors.

Setting Treadmill Intensity for Rat Aerobic Training Using Lactate and Gas Exchange Thresholds

PURPOSE

To open up new horizons of translational research, we studied the lactate threshold (LT)-dependent physiological responses and adaptations to exercise in rats, highlighting the importance of intensity-specific studies for optimizing exercise prescriptions. LT is physiologically related to the noninvasive gas exchange threshold (GET), and both thresholds are moderate-heavy-intensity boundary indices in determining an effective intensity of aerobic training in humans. Although their practical utility is presumed to extend to rats, the actual existence of GET, the thresholds' relations to maximal oxygen consumption (V̇O 2max ), and whether aerobic adaptations by training differ around the LT intensity remain uncertain.

METHODS

This study sought to identify the GET using our previously established rat LT model by combining the use of a metabolic chamber and the V-slope method, and to confirm the thresholds' relations to V̇O 2max . We investigated changes in the thresholds and V̇O 2max following 6 wk of endurance training at below or above LT intensity.

RESULTS

GET and LT were significantly correlated and agreed with high precision, although with a fixed bias. Untrained rats exhibited GET and LT at 56% and 52% of their V̇O 2max , respectively. Endurance training at supra-, but not below-, the LT intensity significantly improved V̇O 2max and both thresholds; however, their %V̇O 2max remained unaltered.

CONCLUSIONS

GET in rats is identifiable as a threshold associated with LT using the V-slope method. Furthermore, both thresholds can serve as moderate-heavy-intensity boundary indices for the aerobic training of rats. This study advances our understanding of exercise intensity regulation in rats, thereby contributing to the development of a more nuanced and effective model for exercise prescription, with implications for human health and fitness.

Using Free-Living Heart Rate Data as an Objective Method to Assess Physical Activity: A Scoping Review and Recommendations by the INTERLIVE-Network Targeting Consumer Wearables

Wearable technologies open up new avenues for the assessment of individual physical activity behaviour. Particularly, free-living heart rate (HR) data assessed by optical sensors are becoming widely available. However, while an abundancy of scientific information and guidance exists for the processing of raw acceleration data, no universal recommendations for the utilization of continuous HR recordings during free-living conditions are available. Towards Intelligent Health and Well-Being: Network of Physical Activity Assessment (INTERLIVE®) is a joint European initiative of six universities and one industrial partner. The consortium was founded in 2019 and strives towards developing best-practice recommendations in the context of consumer wearables and smartphones. The aim of this scoping review (following PRISMA-ScR procedures) and recommendations was to provide best-practice protocols for deriving individual physical activity profiles from continuous HR recordings by wearables. The recommendations were developed through an initial scoping review, grey literature searches of promotional material and user manuals of leading wearable manufacturers as well as evidence-informed discussions among the members of the INTERLIVE®-network. The scoping review was performed on the generic domains required for physical activity assessment, namely: (1) 'assessment of maximal heart rate', (2) 'determination of basal and/or resting heart rate' and (3) 'heart rate-derived intensity zones', for which we finally included a total of 72, 2 and 11 eligible papers, respectively. Gathering recent knowledge, we provide a decision tree and detailed recommendations for the analysis of free-living HR data to derive individual physical activity profiles. Moreover, we also provide examples of HR-metric calculations that help to illustrate data processing and reporting.

Exercise intensity matters: A review on evaluating the effects of aerobic exercise intensity on muscle-derived neuroprotective myokines

Exercise as a medical intervention is effective to help prevent and manage many chronic and complex diseases, including dementia. There is evidence to suggest that regular aerobic exercise protects against age-related brain atrophy and reduces the risk of cognitive decline. The mechanisms by which exercise infers a neuroprotective effect remain to be established but may be related to a maintenance of brain volume and neuronal survival, improved cerebrovascular density and function, and/or increased synaptic plasticity. In addition, there is growing evidence to suggest the beneficial effects of exercise on brain health and cognitive function are, at least in part, mediated by factors released by skeletal muscle during contraction. The fact that the brain responds to exercise suggests that muscle-derived peripheral factors, or "myokines," may play a key role in muscle-brain crosstalk and exercise neuroprotection. However, the most effective "dose" of aerobic exercise to promote beneficial changes in these myokine pathways is currently unknown. Specifically, most of the evidence to date is from studies that have used moderate-intensity exercise, and research investigating the merit of high-intensity exercise is scarce. Considering the well-established role of high-intensity interval training in protecting against numerous medical conditions, more research is needed to identify the most effective "dose" of exercise to improve the beneficial effects of these myokines.

Highlights

Neuroprotection through exercise: Regular aerobic exercise mitigates age-related brain atrophy and cognitive decline via multiple mechanisms, including brain volume maintenance, improved cerebrovascular function, and synaptic plasticity. Myokines as mediators: Muscle-derived factors (myokines) play a crucial role in muscle-brain crosstalk, significantly contributing to the neuroprotective effects of exercise. Intensity matters: The review underscores the necessity to define and study exercise intensity, revealing high-intensity exercise may be as effective, if not more, in promoting neuroprotective myokine levels compared to moderate-intensity exercise. Future research directions: This review emphasizes the need for well-controlled studies to explore the optimal exercise dose for enhancing myokine pathways and their implications for neurodegenerative disease prevention.

Accurate prediction equations for ventilatory thresholds in cardiometabolic disease when gas exchange analysis is unavailable: development and validation

AIMS

To develop and validate equations predicting heart rate (HR) at the first and second ventilatory thresholds (VTs) and an optimized range-adjusted prescription for patients with cardiometabolic disease (CMD). To compare their performance against guideline-based exercise intensity domains.

METHODS AND RESULTS

Cross-sectional study involving 2868 CMD patients from nine countries. HR predictive equations for first and second VTs (VT1, VT2) were developed using multivariate linear regression with 975 cycle-ergometer cardiopulmonary exercise tests (CPET). 'Adjusted' percentages of peak HR (%HRpeak) and HR reserve (%HRR) were derived from this group. External validation with 1893 CPET (cycle-ergometer or treadmill) assessed accuracy, agreement, and reliability against guideline-based %HRpeak and %HRR prescriptions using mean absolute percentage error (MAPE), Bland-Altman analyses, intraclass correlation coefficients (ICC). HR predictive equations (R²: 0.77 VT1, 0.88 VT2) and adjusted %HRR (VT1: 42%, VT2: 77%) were developed. External validation demonstrated superiority over widely used guideline-directed intensity domains for %HRpeak and %HRR. The new methods showed consistent performance across both VTs with lower MAPE (VT1: 7.1%, VT2: 5.0%), 'good' ICC for VT1 (0.81, 0.82) and 'excellent' for VT2 (0.93). Guideline-based exercise intensity domains had higher MAPE (VT1: 6.8-21.3%, VT2: 5.1-16.7%), 'poor' to 'good' ICC for VT1, and 'poor' to 'excellent' for VT2, indicating inconsistencies related to specific VTs across guidelines.

CONCLUSION

Developed and validated HR predictive equations and the optimized %HRR for CMD patients for determining VT1 and VT2 outperformed the guideline-based exercise intensity domains and showed ergometer interchangeability. They offer a superior alternative for prescribing moderate intensity exercise when CPET is unavailable.

The impact of individualised versus standardised endurance and resistance training on the fitness-fatness index in inactive adults

OBJECTIVES

The aim of the current study was to investigate the impact of individualised versus standardised combined endurance and resistance training on the fitness-fatness index in physically inactive adults.

DESIGN

Randomised controlled trial.

METHODS

Fifty-four participants aged 21-55 years were randomised into three groups; 1) non-exercise control (n = 18), 2) standardised moderate-intensity continuous training (n = 18), or 3) individualised moderate-intensity continuous training + high-intensity interval training (n = 18). The fitness-fatness index was calculated by dividing cardiorespiratory fitness (expressed as metabolic equivalents) by the waist-to-height ratio. Participants were classified as likely responders to the intervention if a change of ≥1 fitness-fatness index unit was achieved.

RESULTS

The individualised group showed the greatest fitness-fatness index improvement (between group difference p < 0.001), with 100 % of this group classified as likely responders, compared to the standardised (68 %) and non-exercise control (0 %) groups.

CONCLUSIONS

An individualised, threshold-based exercise programme may produce more favourable changes in the fitness-fatness index than a standardised exercise programme.

Modelling inter-individual variability in acute and adaptive responses to interval training: insights into exercise intensity normalisation

PURPOSE

To investigate the influence of exercise intensity normalisation on intra- and inter-individual acute and adaptive responses to an interval training programme.

METHODS

Nineteen cyclists were split in two groups differing (only) in how exercise intensity was normalised: 80% of the maximal work rate achieved in an incremental test (% W ˙ max) vs. maximal sustainable work rate in a self-paced interval training session (% W ˙ max-SP). Testing duplicates were conducted before and after an initial control phase, during the training intervention, and at the end, enabling the estimation of inter-individual variability in adaptive responses devoid of intra-individual variability.

RESULTS

Due to premature exhaustion, the median training completion rate was 88.8% for the % W ˙ max group, but 100% for the % W ˙ max-SP the group. Ratings of perceived exertion and heart rates were not sensitive to how intensity was normalised, manifesting similar inter-individual variability, although intra-individual variability was minimised for the % W ˙ max-SP group. Amongst six adaptive response variables, there was evidence of individual response for only maximal oxygen uptake (standard deviation: 0.027 L·min-1·week-1) and self-paced interval training performance (standard deviation: 1.451 W·week-1). However, inter-individual variability magnitudes were similar between groups. Average adaptive responses were also similar between groups across all variables.

CONCLUSIONS

To normalise completion rates of interval training, % W ˙ max-SP should be used to prescribe relative intensity. However, the variability in adaptive responses to training may not reflect how exercise intensity is normalised, underlining the complexity of the exercise dose-adaptation relationship. True inter-individual variability in adaptive responses cannot always be identified when intra-individual variability is accounted for.

The Impact of Personalized versus Standardized Cardiorespiratory and Muscular Training on Health-Related Outcomes and Rate of Responders

Recent research has shown more favorable training adaptations for inactive adults when cardiorespiratory fitness (CRF) exercise is prescribed with the use of ventilatory thresholds compared to percentages of heart rate reserve (HRR). However, there is limited research on changes in health-related outcomes with the use of these CRF methods in combination with muscular fitness exercises. The objective of this study was to compare the effectiveness of two training programs for improving CRF, muscular fitness, and cardiometabolic risk factors. Inactive men and women (n=109, aged 49.3±15.5 years) were randomized to a non-exercise control group or one of two exercise training groups. The exercise training groups consisted of 13 weeks of structured exercise with progression using either CRF exercise prescribed with the use of ventilatory thresholds and functional training for muscular fitness (THRESH group) or HRR and traditional muscular fitness training (STND group). After the 13-week protocol, there were significant differences in body weight, body composition, systolic blood pressure, high-density lipoprotein cholesterol (HDL-c), VO2max, 5-repetition maximum (RM) bench press, and 5-RM leg press for both treatment groups compared to the control group after controlling for baseline values. However, the THRESH group had significantly more desirable outcomes for VO2max, 5-RM bench press, 5-RM leg press, body composition, and HDL-c when compared to both the STND and control group. Additionally, the proportion of individuals estimated as likely to respond above 3.5 mL·kg-1·min-1 in VO2max (i.e., the minimal clinically important difference) was 76.4%, 20.8%, and 0.13% for the THRESH, STND, and control groups, respectively. While both exercise programs elicited favorable health-related adaptations after 13 weeks, these results suggest that a personalized program with exercise prescribed based on ventilatory threshold and with the use of functional muscular fitness training may yield greater training adaptations.

Exercise and Acute Affect

The study of the affective impact of physical activity and exercise has a long and fraught history. In this chapter we outline some of the longstanding issues, in the hopes that research moving forward will be more mindful of these. Included are: (a) what we are actually trying to assess; (b) measurement issues; (c) the timing of affective measurement; (d) research that highlights what we know and don't know; and (e) suggestions for moving forward.

The effects of inorganic nitrate supplementation on exercise economy and endurance capacity across the menstrual cycle

Oral inorganic nitrate (NO3-) supplementation has been shown to increase bioavailable NO and provide potential ergogenic benefits in males; however, data in females is scarce. Estrogen is known to increase endogenous NO bioavailability and to fluctuate throughout the menstrual cycle (MC), being lowest in the early follicular (EF) phase and highest during the late follicular (LF) phase. This study examined the effects of oral NO3- supplementation on exercise economy, endurance capacity, and vascular health in young females across the MC. Ten normally menstruating females' MCs were tested in a double-blinded, randomized design during both the EF and LF phases of the MC. Participants consumed ∼13 mmol NO3-, in the form of 140 mL beetroot juice (BRJ) or an identical NO3--depleted placebo (PL) for ∼3 days before lab visits and 2 h before testing on lab visits. Plasma nitrate, nitrite, and estradiol were assessed, as was blood pressure and pulse wave velocity. Moderate-intensity exercise economy and severe intensity time to exhaustion (TTE) were tested on a cycle ergometer. As expected, plasma estradiol was elevated in the LF phase, and plasma nitrite and nitrate were elevated in the BRJ condition. Exercise economy was unaltered by BRJ or the MC, however TTE was significantly worsened by 48 s (∼10%) after BRJ supplementation (P = 0.04), but was not different across the MC with no interaction effects. In conclusion, NO3- supplementation did not affect exercise economy or vascular health and worsened aerobic endurance capacity (TTE), suggesting healthy females should proceed with caution when considering supplementation with BRJ.NEW & NOTEWORTHY Although inorganic nitrate (NO3-) supplementation has increased in popularity as a means of improving exercise performance, data in females at different phases of the menstrual cycle are lacking despite known interactions of estrogen with NO. This study revealed neither NO3- supplementation nor the menstrual cycle influenced exercise economy or vascular health in healthy young naturally menstruating females, while NO3- supplementation significantly worsened endurance capacity (10%) independent of the menstrual cycle phase.

Cardiorespiratory Parameters Comparison Between Incremental Protocols Performed in Aquatic and Land Environments by Healthy Individuals: A Systematic Review and Meta-Analysis

BACKGROUND

Physical properties of water cause physiological changes in the immersed human body compared with the land environment. Understanding the magnitude of cardiorespiratory alterations might ensure adequate intensity control during aquatic exercise programs.

OBJECTIVE

We aimed to compare the oxygen uptake (VO2), heart rate (HR), and rating of perceived exertion (RPE) parameters during aquatic and land incremental tests.

METHODS

Four databases (PubMed, LILACS, EMBASE, and SPORTDiscus) were searched in September 2020. Eligibility criteria included studies in a crossover design comparing aquatic and land incremental tests for healthy individuals with at least one of the following parameters: VO2 (maximal, VO2max; anaerobic threshold, VO2AT), HR (HRmax; HRAT), and RPE (RPEmax; RPEAT). The random-effects meta-analysis included mean difference and 95% confidence interval for VO2 and HR or standardized mean difference for RPE. The Joanna Briggs Institute Critical Appraisal tool was adapted to assess methodological quality.

RESULTS

Twenty-eight studies were eligible and included in the meta-analysis. Aquatic protocols showed lower values compared with land for VO2max (- 7.07 mL.kg-1.min-1; - 8.43 to - 5.70; n = 502), VO2AT (- 6.19 mL.kg-1.min-1; - 7.66 to - 4.73; n = 145), HRmax (- 11.71 bpm; - 13.84 to - 9.58; n = 503), and HRAT (- 15.29 bpm; - 19.05 to - 11.53; n = 145). RPEmax (0.01; - 0.16 to 0.18; n = 299) and RPEAT (- 0.67; - 1.35 to 0.02; n = 55) values were similar between aquatic and land protocols.

CONCLUSIONS

Our study reinforces the specificity of the environment during incremental tests for prescribing exercises based on physiological parameters as VO2 and HR parameters presented lower values in aquatic protocols than land protocols. Conversely, RPE seems an interchangeable measure of exercise intensity, with similar values during the protocols in both environments. Substantial levels of heterogeneity were present for the VO2max and HRmax meta-analyses, and as such, results should be interpreted with attention. PROTOCOL REGISTRATION: This study was registered in the International Prospective Register of Systematic Reviews (PROSPERO; CRD42020212508).

An Examination and Critique of Subjective Methods to Determine Exercise Intensity: The Talk Test, Feeling Scale, and Rating of Perceived Exertion

Prescribing exercise intensity is crucial in achieving an adequate training stimulus. While numerous objective methods exist and are used in practical settings for exercise intensity prescription, they all require anchor measurements that are derived from a maximal or submaximal graded exercise test or a series of submaximal or supramaximal exercise bouts. Conversely, self-reported subjective methods such as the Talk Test (TT), Feeling Scale (FS) affect rating, and rating of perceived exertion (RPE) do not require exercise testing prior to commencement of the exercise training and therefore appear as more practical tools for exercise intensity prescription. This review is intended to provide basic information on reliability and construct validity of the TT, FS, and RPE measurements to delineate intensity domains. The TT and RPE appear to be valid measures of both the ventilatory threshold and the respiratory compensation threshold. Although not specifically examined, the FS showed tendency to demarcate ventilatory threshold, but its validity to demarcate the respiratory compensation threshold is limited. Equivocal stage of the TT, RPE of 10-11, and FS ratings between fairly good (+ 1) and good (+ 3) are reflective of the ventilatory threshold, while negative stage of the TT, RPE of 13-15, and FS ratings around neutral (0) are reflective of the respiratory compensation threshold. The TT and RPE can effectively be used to elicit homeostatic disturbances consistent with the moderate, heavy, and severe intensity domains, while physiological responses to constant FS ratings show extensive variability around ventilatory threshold to be considered effective in demarcating transition between moderate and heavy intensity domains.

Exercise Training Intensity and the Fitness-Fatness Index in Adults with Metabolic Syndrome: A Randomized Trial

Background

Cardiorespiratory fitness and fatness (notably central obesity) are mediating factors of the metabolic syndrome (MetS) and consequent cardiovascular disease (CVD)/mortality risk. The fitness-fatness index (FFI) combines these factors and has been reported to be a better indicator of CVD and all-cause mortality risk, beyond the capacity of either fitness or fatness alone.

Objective

This study sought to investigate the effects of different exercise intensities on FFI in adults with MetS.

Methods

This was a sub-study of the ‘Exercise in the prevention of Metabolic Syndrome’ (EX-MET) multicentre trial. Ninety-nine adults diagnosed with MetS according to the International Diabetes Federation criteria were randomized to one of the following 16-week exercise interventions: i) moderate-intensity continuous training (MICT) at 60–70% HRpeak for 30 min/session (n = 34, 150 min/week); ii) 4 × 4 min bouts of high-intensity interval training at 85–95% HRpeak, interspersed with 3-min active recovery at 50–70% HRpeak (n = 34, 38 min/session, 114 min/week); and iii) 1 × 4 min bout of HIIT at 85–95% HRpeak (n = 31, 17 min/session, 51 min/week). Cardiorespiratory fitness (peak oxygen uptake, V̇O2peak) was determined via indirect calorimetry during maximal exercise testing and fatness was the ratio of waist circumference-to-height (WtHR). FFI was calculated as V̇O2peak in metabolic equivalents (METs) divided by WtHR. A clinically meaningful response to the exercise intervention was taken as a 1 FFI unit increase.

Results

Seventy-seven participants completed pre and post testing to determine FFI. While there was no significant between group difference (p = 0.30), there was a small group x time interaction effect on FFI [F(2, 73) = 1.226; η2 = 0.01], with numerically greater improvements following HIIT (4HIIT, + 16%; 1HIIT, + 11%) relative to MICT (+ 7%). There was a greater proportion of participants who had a clinically meaningful change in FFI following high-volume HIIT (60%, 15/25) and low-volume HIIT (65%, 17/26) compared to MICT (38%, 10/26), but with no significant between-group difference (p = 0.12). A similar trend was found when a sub-analysis comparing the FFI between those with type 2 diabetes (MICT, 33%, 3/9; high-volume HIIT, 64%, 7/11; and low-volume HIIT, 58%, 7/12) and without type 2 diabetes (MICT, 41%, 7/17; high-volume HIIT, 57%, 8/14; low-volume HIIT, 71%, 10/14).

Conclusion

Although there were no statistically significant differences detected between groups, this study suggests that the response to changes in FFI in adults with MetS may be affected by exercise intensity, when numerical differences between exercise groups are considered. Further research is warranted.

Trial registration number and date of registration: ClinicalTrials.gov NCT01676870; 31/08/2012.

The importance of ventilatory thresholds to define aerobic exercise intensity in cardiac patients and healthy subjects

BACKGROUND

Although structured exercise training is strongly recommended in cardiac patients, uncertainties exist about the methods for determining exercise intensity (EI) and their correspondence with effective EI obtained by ventilatory thresholds. We aimed to determine the first (VT1 ) and second ventilatory thresholds (VT2 ) in cardiac patients, sedentary subjects, and athletes comparing VT1 and VT2 with EI defined by recommendations.

METHODS

We prospectively enrolled 350 subjects (mean age: 50.7±12.9 years; 167 cardiac patients, 150 healthy sedentary subjects, and 33 competitive endurance athletes). Each subject underwent ECG, echocardiography, and cardiopulmonary exercise testing. The percentages of peak VO2 , peak heart rate (HR), and HR reserve were obtained at VT1 and VT2 and compared with the EI definition proposed by the recommendations.

RESULTS

VO2 at VT1 corresponded to high rather than moderate EI in 67.1% and 79.6% of cardiac patients, applying the definition of moderate exercise by the previous recommendations and the 2020 guidelines, respectively. Most cardiac patients had VO2  values at VT2 corresponding to very-high rather than high EI (59.9% and 50.3%, by previous recommendations and 2020 guidelines, respectively). A better correspondence between ventilatory thresholds and recommended EI domains was observed in healthy subjects and athletes (90% and 93.9%, respectively).

CONCLUSIONS

EI definition based on percentages of peak HR and peak VO2  may misclassify the effective EI, and the discrepancy between the individually determined and the recommended EI is particularly relevant in cardiac patients. A ventilatory threshold-based rather than a range-based approach is advisable to define an appropriate level of EI.

Anaerobic Threshold in a Water-Based Exercise: Agreement Between Heart Rate Deflection Point and Lactate Threshold Methods

ABSTRACT

Alberton, CL, Andrade, LS, Pinheiro, RB, and Pinto, SS. Anaerobic threshold in a water-based exercise: agreement between heart rate deflection point and lactate threshold methods. J Strength Cond Res 35(9): 2472-2478, 2021-The purpose of this study was to compare and assess the agreement of the heart rate (HR) and rating of perceived exertion (RPE) corresponding to the anaerobic threshold (AT) between HR deflection point (HRDP) and lactate threshold (LT) methods during a water-based exercise in young men. Sixteen young men (24 ± 6 years) performed the experimental protocol, which comprised the performance of a maximal incremental test during the water-based stationary running exercise. The initial cadence corresponded to 90 b·min-1, with 10 b·min-1 increases every 3 minutes up to exhaustion. Heart rate was monitored every 30 seconds while blood lactate concentrations and RPE were measured at the end of each 3-minute bout. Anaerobic threshold was identified by HRDP and LT methods by experienced physiologists. Paired Student's t-test, Bland-Altman analysis, and Pearson correlation were used for data analysis (α = 0.05). As results, there was agreement between HRDP and LT methods for HR, while RPE presented significant higher values for the HRDP method, resulting in an absence of acceptable agreement between methods. In addition, strong relationships (p ≤ 0.001) were verified between methods of AT determination for HR (r = 0.786) and RPE (r = 0.916). Therefore, based on the agreement between HRDP and LT methods, the HR determined by HRDP may be a valid parameter used for the intensity prescription of water-based stationary running exercise in young men during water aerobics programs and may be considered more reliable than RPE.

Biological and methodological factors affecting V ̇ O 2 max response variability to endurance training and the influence of exercise intensity prescription

NEW FINDINGS

What is the topic of this review? Biological and methodological factors associated with the variable changes in cardiorespiratory fitness in response to endurance training. What advances does it highlight? Several biological and methodological factors exist that each contribute, to a given extent, to response variability. Notably, prescribing exercise intensity relative to physiological thresholds reportedly increases cardiorespiratory fitness response rates compared to when prescribed relative to maximum physiological values. As threshold-based approaches elicit more homogeneous acute physiological responses among individuals, when repeated over time, these uniform responses may manifest as more homogeneous chronic adaptations thereby reducing response variability.

ABSTRACT

Changes in cardiorespiratory fitness (CRF) in response to endurance training (ET) exhibit large variations, possibly due to a multitude of biological and methodological factors. It is acknowledged that ∼20% of individuals may not achieve meaningful increases in CRF in response to ET. Genetics, the most potent biological contributor, has been shown to explain ∼50% of response variability, whilst age, sex and baseline CRF appear to explain a smaller proportion. Methodological factors represent the characteristics of the ET itself, including the type, volume and intensity of exercise, as well as the method used to prescribe and control exercise intensity. Notably, methodological factors are modifiable and, upon manipulation, alter response rates to ET, eliciting increases in CRF regardless of an individual's biological predisposition. Particularly, prescribing exercise intensity relative to a physiological threshold (e.g., ventilatory threshold) is shown to increase CRF response rates compared to when intensity is anchored relative to a maximum physiological value (e.g., maximum heart rate). It is, however, uncertain whether the increased response rates are primarily attributable to reduced response variability, greater mean changes in CRF or both. Future research is warranted to elucidate whether more homogeneous chronic adaptations manifest over time among individuals, as a result of exposure to more homogeneous exercise stimuli elicited by threshold-based practices.

Variability in Submaximal Self-Paced Exercise Bouts of Different Intensity and Duration

PURPOSE

Rating of perceived exertion (RPE) as a training-intensity prescription has been extensively used by athletes and coaches. However, individual variability in the physiological response to exercise prescribed using RPE has not been investigated.

METHODS

Twenty well-trained competitive cyclists (male = 18, female = 2, maximum oxygen consumption =55.07 [11.06] mL·kg-1·min-1) completed 3 exercise trials each consisting of 9 randomized self-paced exercise bouts of either 1, 4, or 8 minutes at RPEs of 9, 13, and 17. Within-athlete variability (WAV) and between-athletes variability (BAV) in power and physiological responses were calculated using the coefficient of variation. Total variability was calculated as the ratio of WAV to BAV.

RESULTS

Increased RPEs were associated with higher power, heart rate, work, volume of expired oxygen (VO2), volume of expired carbon dioxide (VCO2), minute ventilation (VE), deoxyhemoglobin (ΔHHb) (P < .001), and lower tissue saturation index (ΔTSI%) and ΔO2Hb (oxyhaemoglobin; P < .001). At an RPE of 9, shorter durations resulted in lower VO2 (P < .05) and decreased ΔTSI%, and the ΔHHb increased as the duration increased (P < .05). At an RPE of 13, shorter durations resulted in lower VO2, VE, and percentage of maximum oxygen consumption (P < .001), as well as higher power, heart rate, ΔHHb (P < .001), and ΔTSI% (P < .05). At an RPE of 17, power (P < .001) and ΔTSI% (P < .05) increased as duration decreased. As intensity and duration increased, WAV and BAV in power, work, heart rate, VO2, VCO2, and VE decreased, and WAV and BAV in near-infrared spectroscopy increased.

CONCLUSIONS

Self-paced intensity prescriptions of high effort and long duration result in the greatest consistency on both a within- and between-athletes basis.

Relationship between the face scale for rating of perceived exertion and physiological parameters in older adults and patients with atrial fibrillation

BACKGROUND

The Borg scale is used to determine exercise intensity in rehabilitation but can be difficult for older adults to understand. By contrast, face scale that are used to evaluate pain are much easier to understand thanks to the inclusion of illustrations. On the other hand, the prevalence of atrial fibrillation (AF) increases with age. This study aimed to determine the validity of the face scale for rating perceived exertion (RPE-face scale) in older adults and patients with AF during cardiopulmonary exercise test. Furthermore, the relationship between face scale and anaerobic threshold (AT) was also investigated.

METHODS

A total of 90 patients with sinus rhythm (SR) (74 men, 16 women) and 22 with AF were enrolled. Participants' responses were recorded using the RPE-face scale and compared with exercise intensity, heart rate, oxygen uptake, and minute ventilation during the exercise test. We determined the AT by the V-slope method.

RESULTS

Correlations between RPE-face scale and physiological parameters were significantly positive for men with SR and women with SR and AF. However, differences in the correlation coefficient between age and SR or AF were not statistically significant. The cutoff value for AT of the RPE-face scale was "4," showing high sensitivity and specificity.

CONCLUSIONS

The RPE-face scale can be used to determine the intensity of physical exercise, unaffected by age, gender, SR, or AF.

25 Years of Session Rating of Perceived Exertion: Historical Perspective and Development

The session rating of perceived exertion (sRPE) method was developed 25 years ago as a modification of the Borg concept of rating of perceived exertion (RPE), designed to estimate the intensity of an entire training session. It appears to be well accepted as a marker of the internal training load. Early studies demonstrated that sRPE correlated well with objective measures of internal training load, such as the percentage of heart rate reserve and blood lactate concentration. It has been shown to be useful in a wide variety of exercise activities ranging from aerobic to resistance to games. It has also been shown to be useful in populations ranging from patients to elite athletes. The sRPE is a reasonable measure of the average RPE acquired across an exercise session. Originally designed to be acquired ∼30 minutes after a training bout to prevent the terminal elements of an exercise session from unduly influencing the rating, sRPE has been shown to be temporally robust across periods ranging from 1 minute to 14 days following an exercise session. Within the training impulse concept, sRPE, or other indices derived from sRPE, has been shown to be able to account for both positive and negative training outcomes and has contributed to our understanding of how training is periodized to optimize training outcomes and to understand maladaptations such as overtraining syndrome. The sRPE as a method of monitoring training has the advantage of extreme simplicity. While it is not ideal for the precise recording of the details of the external training load, it has large advantages relative to evaluating the internal training load.

HRR and V˙O2R Fractions Are Not Equivalent: Is It Time to Rethink Aerobic Exercise Prescription Methods?

INTRODUCTION

According to current guidelines, the intensity of health-enhancing aerobic exercise should be prescribed using a percentage of heart rate reserve (%HRR), which is considered to be more closely associated (showing a 1:1 relation) with the percentage of oxygen uptake reserve (%V˙O2R) rather than with the percentage of maximal oxygen uptake (%V˙O2max) during incremental exercise. However, the associations between %HRR and %V˙O2R and between %HRR and %V˙O2max are under debate; hence, their actual relationships were investigated in this study.

METHODS

Data from each stage of a maximal incremental exercise test performed by 737 healthy and physically inactive participants of the HERITAGE Family Study were screened and filtered then used to calculate the individual linear regressions between %HRR and either %V˙O2R or %V˙O2max. For each relationship, the mean slope and intercept of the individual linear regression were compared with 1 and 0 (i.e., the identity line), respectively, using one-sample t-tests. The individual root mean square errors of the actual versus the 1:1 predicted %HRR were calculated for both relationships and compared using a paired-sample t-test.

RESULTS

The mean slopes (%HRR-%V˙O2R, 0.972 ± 0.189; %HRR-%V˙O2max, 1.096 ± 0.216) and intercepts (%HRR-%V˙O2R, 8.855 ± 16.022; %HRR-%V˙O2max, -3.616 ± 18.993) of both relationships were significantly different from 1 and 0, respectively, with high interindividual variability. The average root mean square errors were high and revealed that the %HRR-%V˙O2max relationship was more similar to the identity line (P < 0.001) than the %HRR-%V˙O2R relationship (7.78% ± 4.49% vs 9.25% ± 5.54%).

CONCLUSIONS

Because both relationships are different from the identity line and using a single equation may not be appropriate to predict exercise intensity at the individual level, a rethinking of the relationships between the intensity variables may be necessary to ensure that the most suitable health-enhancing aerobic exercise intensity is prescribed.

Effectiveness of physical exercise for people with chronic diseases: the EFIKRONIK study protocol for a hybrid, clinical and implementation randomized trial

Background

Chronic illnesses are the leading cause of morbidity and mortality and threaten the sustainability of healthcare systems worldwide. There is limited evidence in terms of the best modality and intensity of physical activity for improving cardiorespiratory capacity and quality of life in patients with chronic conditions. The objective of the EfiKroniK study is to estimate the common effect of innovative, individualized and supervised physical exercise, on cardiorespiratory functional capacity and quality of life across people with different chronic conditions.

Methods/design

This is a multicentre clinical trial with a type I hybrid effectiveness-implementation design, including 370 patients each with one of four different chronic illnesses: solid cancer, blood cancer, chronic obstructive pulmonary disease or schizophrenia. Patients will be randomly divided into two parallel groups, stratified by illness type. Patients in both groups will receive a standard healthy life prescription (PVS, from the Spanish “Prescribe Vida Saludable”) and additionally, the EfiKroniK group will be prescribed a physical exercise programme tailored to each patient in terms of intensity in each session. The primary outcome variables will be cardiorespiratory functional capacity and quality of life. The secondary outcome variables will be signs and symptoms, psychological and social factors and specific laboratory parameters. We will also analyse the dose-response effect of the physical exercise programme. Qualitative variables will describe patients’ perception of the utility and suitability of the EfiKroniK programme, as well as their expectations and satisfaction, identifying barriers to and facilitators of the EfiKroniK implementation process through discussion groups. The study will be carried out on an intention-to-treat basis, comparing changes throughout the 1-year follow-up between groups, adjusting for baseline, by performing mixed-effect analysis of covariance. We will estimate the effect of time on repeated measures in each subject and changes in the EfiKroniK and PVS groups over time.

Discussion

The study will provide the data necessary to allow us to prescribe physical exercise in a similar way to a drug and as a key part of the treatment of chronic illnesses within our healthcare system.

Trial registration

NCT03810755.

Date and version identifier: October 9, 2020. Version2.0.

Generalized Approach to Translating Exercise Tests and Prescribing Exercise

Although there is evidence supporting the benefit of regular exercise, and recommendations about exercise and physical activity, the process of individually prescribing exercise following exercise testing is more difficult. Guidelines like % heart rate (HR) reserve (HRR) require an anchoring maximal test and do not always provide a homogenous training experience. When prescribing HR on the basis of % HRR, rating of perceived exertion or Talk Test, cardiovascular/perceptual drift during sustained exercise makes prescription of the actual workload difficult. To overcome this issue, we have demonstrated a strategy for "translating" exercise test responses to steady state exercise training on the basis of % HRR or the Talk Test that appeared adequate for individuals ranging from cardiac patients to athletes. However, these methods depended on the nature of the exercise test details. In this viewpoint, we combine these data with workload expressed as Metabolic Equivalent Task (METs). We demonstrate that there is a regular stepdown between the METs during training to achieve the same degree of homeostatic disturbance during testing. The relationship was linear, was highly-correlated (r = 0.89), and averaged 71.8% (Training METs/Test METs). We conclude that it appears possible to generate a generalized approach to correctly translate exercise test responses to exercise training.

A Discussion on Different Approaches for Prescribing Physical Interventions - Four Roads Lead to Rome, but Which One Should We Choose?

It is well recognized that regular physical exercise has positive effects on physical and mental health. To use the beneficial health effects of physical exercise, there are worldwide movements encouraging health care providers to include physical exercise in their care and treatments strategies. However, a crucial point in administering the "exercise polypill" is the dosing and, in turn, the prescription of the physical intervention (PI). In this perspective article, we discuss the advantages and disadvantages of different approaches to prescribe PI. In this context, we also highlight outstanding questions and potential areas of opportunity for further investigations.

New Directions in Exercise Prescription: Is There a Role for Brain-Derived Parameters Obtained by Functional Near-Infrared Spectroscopy?

In the literature, it is well established that regular physical exercise is a powerful strategy to promote brain health and to improve cognitive performance. However, exact knowledge about which exercise prescription would be optimal in the setting of exercise–cognition science is lacking. While there is a strong theoretical rationale for using indicators of internal load (e.g., heart rate) in exercise prescription, the most suitable parameters have yet to be determined. In this perspective article, we discuss the role of brain-derived parameters (e.g., brain activity) as valuable indicators of internal load which can be beneficial for individualizing the exercise prescription in exercise–cognition research. Therefore, we focus on the application of functional near-infrared spectroscopy (fNIRS), since this neuroimaging modality provides specific advantages, making it well suited for monitoring cortical hemodynamics as a proxy of brain activity during physical exercise.

Incidence of V˙O2max Responders to Personalized versus Standardized Exercise Prescription

INTRODUCTION

Despite knowledge of cardiorespiratory fitness (CRF) training responders and nonresponders, it is not well understood how the exercise intensity prescription affects the incidence of response. The purpose of this study was to determine CRF training responsiveness based on cohort-specific technical error after 12 wk of standardized or individually prescribed exercise and the use of a verification protocol to confirm maximal oxygen uptake (V˙O2max).

METHODS

Sedentary adult participants (9 men, 30 women; 48.2 ± 12.2 yr) completed exercise training on 3 d·wk for 12 wk, with exercise intensity prescribed based on standardized methods using heart rate reserve or an individualized approach using ventilatory thresholds. A verification protocol was used at baseline and 12 wk to confirm the identification of a true V˙O2max and subsequent relative percent changes to quantify CRF training responsiveness. A cohort-specific technical error (4.7%) was used as a threshold to identify incidence of response.

RESULTS

Relative V˙O2max significantly increased (P < 0.05) from 24.3 ± 4.6 to 26.0 ± 4.2 and 29.2 ± 7.5 to 32.8 ± 8.6 mL·kg·min for the standardized and individualized groups, respectively. Absolute V˙O2max significantly increased (P < 0.05) from 2.0 ± 0.6 to 2.2 ± 0.6 and 2.4 ± 0.8 to 2.6 ± 0.9 L·min for the standardized and individualized groups, respectively. A significant difference in responsiveness was found between the individualized and standardized groups with 100% and 60% of participants categorized as responders, respectively.

CONCLUSIONS

A threshold model for exercise intensity prescription had a greater effect on the incidence of CRF training response compared with a standardized approach using heart rate reserve. The use of thresholds for intensity markers accounts for individual metabolic characteristics and should be considered as a viable and practical method to prescribe exercise intensity.

Dose-Response Matters! - A Perspective on the Exercise Prescription in Exercise-Cognition Research

In general, it is well recognized that both acute physical exercises and regular physical training influence brain plasticity and cognitive functions positively. However, growing evidence shows that the same physical exercises induce very heterogeneous outcomes across individuals. In an attempt to better understand this interindividual heterogeneity in response to acute and regular physical exercising, most research, so far, has focused on non-modifiable factors such as sex and different genotypes, while relatively little attention has been paid to exercise prescription as a modifiable factor. With an adapted exercise prescription, dosage can be made comparable across individuals, a procedure that is necessary to better understand the dose-response relationship in exercise-cognition research. This improved understanding of dose-response relationships could help to design more efficient physical training approaches against, for instance, cognitive decline.

A Randomized Controlled Trial Investigating the Effects of Undulatory, Staggered, and Linear Load Manipulations in Aerobic Training on Oxygen Supply, Muscle Injury, and Metabolism in Male Recreational Runners

Background

Taper is considered as a strategy to avoid overtraining and increase peak performance in athletes. Because aerobic exercise increases the level and duration of independence during the lifespan, the participation of recreational athletes has increased in running events around the world. However, the effects of using load reduction in their training and aerobic performance are still not well known.

Objectives

Our goal was to compare load manipulations, using tapering-like periods in the end of recreational athletes training evaluating alterations in oxygen supply, muscle injury, and metabolism markers.

Methods

Healthy males (n = 88, 20–35 years old) were randomly distributed in groups using a combination of two mesocycles of 4 weeks, undulatory and staggered, with two daily microcycles, undulatory and linear. Undulatory-undulatory (Und-Und) and undulatory-linear (Und-Lin) groups had load reduction in the final week of training while the staggered-undulatory (Sta-Und) and staggered-linear (Sta-Lin) groups did not. Cardiorespiratory capacity (V̇O_2max), body mass index (BMI), and body fat % were evaluated. Blood samples were also collected to analyze hematocrit (Ht), mean corpuscular hemoglobin (MCHC), circulating levels of hemoglobin (Hb), creatine kinase (CK), lactate dehydrogenase (LDH), aspartate aminotransferase (AST), alanine aminotransferase (ALT), urea (U), cortisol (C), free testosterone (FT), and free T/C ratio.

Results

After 8 weeks of training, Und-Und had the highest trend to increase V̇O_2max. Both Und-Und and Sta-Lin reduced body fat %. Und-Und showed a significant increase in MCHC, T and Free T/C ratio, a positive trend to increase Ht% and Hb levels, and a trend to decrease CK, LDH, and C circulating levels. Sta-Lin presented a trend to decrease Ht% and Hb levels, a significant increase in CK, LDH, AST, ALT circulating levels, and a decrease in Free T/C ratio.

Conclusion

The use of daily undulatory training load provides better gains for aerobic fitness while the use of staggered load, mainly associated with linear load, promotes inadequate recovery in recreational runners.

Personalized Moderate-Intensity Exercise Training Combined with High-Intensity Interval Training Enhances Training Responsiveness

This study sought to determine if personalized moderate-intensity continuous exercise training (MICT) combined with high-intensity interval training (HIIT) was more effective at improving comprehensive training responsiveness than MICT alone. Apparently healthy, but physically inactive men and women (n = 54) were randomized to a non-exercise control group or one of two 13-week exercise training groups: (1) a personalized MICT + HIIT aerobic and resistance training program based on the American Council on Exercise guidelines, or (2) a standardized MICT aerobic and resistance training program designed according to current American College of Sports Medicine guidelines. Mean changes in maximal oxygen uptake (VO_2max) and Metabolic (MetS) z-score in the personalized MICT + HIIT group were more favorable (p < 0.05) when compared to both the standardized MICT and control groups. Additionally, on the individual level, there were positive improvements in VO_2max (Δ > 4.9%) and MetS z-score (Δ ≤ -0.48) in 100% (16/16) of participants in the personalized MICT + HIIT group. In the present study, a personalized exercise prescription combining MICT + HIIT in conjunction with resistance training elicited greater improvements in VO_2max, MetS z-score reductions, and diminished inter-individual variation in VO_2max and cardiometabolic training responses when compared to standardized MICT.

Time Course Changes in Confirmed 'True' VO 2 max After Individualized and Standardized Training

This study sought to examine time course changes in maximal oxygen consumption (VO ₂ max) confirmed with verification testing following 12 weeks of standardized vs. individualized exercise training. Participants (N=39) were randomly allocated to differing exercise intensity prescription groups: ventilatory threshold (individualized) or % heart rate reserve (standardized). At baseline, 4, 8, and 12 weeks, participants completed maximal exercise testing with a verification protocol to confirm ‘true VO ₂ max.’ VO ₂ max in the standardized group changed from 24.3±4.6 ml·kg ⁻¹ ·min ⁻¹ at baseline to 24.7±4.6, 25.9±4.7, and 26.0±4.2 ml·kg ⁻¹ ·min ⁻¹ at week 4, 8, and 12, respectively, with a significant difference (p<0.05) in VO ₂ max at week 8 and 12 compared to baseline. The individualized group had increases in VO ₂ max from _{online 2} 9.5±7.5 ml·kg ⁻¹ ·min ⁻¹ at baseline to 30.6±8.4, 31.4±8.4, and 32.8±8.6 ml·kg ⁻¹ ·min ⁻¹ at week 4, 8, and 12, respectively. In the individualized group, there were significant differences (p<0.05) in VO ₂ max from baseline to week 8 and 12 and a significant increase in VO ₂ max from week 8 to 1 _{online 2} . Although not statistically significant, our preliminary data demonstrates a more rapid and potent improvement in VO ₂ max when exercise intensity is individualized. This is the first investigation to employ use of the verification procedure to confirm ‘true VO ₂ max’ changes following exercise training using ventilatory thresholds.

Does exercise prescription based on estimated heart rate training zones exceed the ventilatory anaerobic threshold in patients with coronary heart disease undergoing usual-care cardiovascular rehabilitation? A United Kingdom perspective

Background

In the United Kingdom (UK), exercise intensity is prescribed from a fixed percentage range (% heart rate reserve (%HRR)) in cardiac rehabilitation programmes. We aimed to determine the accuracy of this approach by comparing it with an objective, threshold-based approach incorporating the accurate determination of ventilatory anaerobic threshold (VAT). We also aimed to investigate the role of baseline cardiorespiratory fitness status and exercise testing mode dependency (cycle vs. treadmill ergometer) on these relationships.

Design and methods

A maximal cardiopulmonary exercise test was conducted on a cycle ergometer or a treadmill before and following usual-care circuit training from two separate cardiac rehabilitation programmes from a single region in the UK. The heart rate corresponding to VAT was compared with current heart rate-based exercise prescription guidelines.

Results

We included 112 referred patients (61 years (59–63); body mass index 29 kg·m–2 (29–30); 88% male). There was a significant but relatively weak correlation ( r = 0.32; p = 0.001) between measured and predicted %HRR, and values were significantly different from each other ( p = 0.005). Within this cohort, we found that 55% of patients had their VAT identified outside of the 40–70% predicted HRR exercise training zone. In the majority of participants (45%), the VAT occurred at an exercise intensity <40% HRR. Moreover, 57% of patients with low levels of cardiorespiratory fitness achieved VAT at <40% HRR, whereas 30% of patients with higher fitness achieved their VAT at >70% HRR. VAT was significantly higher on the treadmill than the cycle ergometer ( p < 0.001).

Conclusion

In the UK, current guidelines for prescribing exercise intensity are based on a fixed percentage range. Our findings indicate that this approach may be inaccurate in a large proportion of patients undertaking cardiac rehabilitation.

Predicting oxygen uptake responses during cycling at varied intensities using an artificial neural network

Study aim: Oxygen Uptake (VO2) is avaluable metric for the prescription of exercise intensity and the monitoring of training progress. However, VO2 is difficult to assess in anon-laboratory setting. Recently, an artificial neural network (ANN) was used to predict VO2 responses during aset walking protocol on the treadmill [9]. The purpose of the present study was to test the ability of an ANN to predict VO2 responses during cycling at self-selected intensities using Heart Rate (HR), time derivative of HR, power output, cadence, and body mass data.

Material and methods: 12 moderately-active adult males (age: 21.1 ± 2.5 years) performed a50-minute bout of cycling at a variety of exercise intensities. VO2, HR, power output, and cadence were recorded throughout the test. An ANN was trained, validated and tested using the following inputs: HR, time derivative of HR, power output, cadence, and body mass. A twelve-fold hold-out cross validation was conducted to determine the accuracy of the model.

Results: The ANN accurately predicted the experimental VO2 values throughout the test (R2 = 0.91 ± 0.04, SEE = 3.34 ± 1.07 mL/kg/min).

Discussion: This preliminary study demonstrates the potential for using an ANN to predict VO2 responses during cycling at varied intensities using easily accessible inputs. The predictive accuracy is promising, especially considering the large range of intensities and long duration of exercise. Expansion of these methods could allow ageneral algorithm to be developed for a more diverse population, improving the feasibility of oxygen uptake assessment.

The relationship between ventilatory threshold and repeated-sprint ability in competitive male ice hockey players

Background/objective

The relationship between ventilatory threshold (VT1, VT2) and repeated-sprint ability (RSA) in competitive male ice hockey players was investigated.

Methods

Forty-three male ice hockey players aged 18-23 years competing in NCAA Division I, NCAA Division III, and Junior A level participated. Participants performed an incremental graded exercise test on a skate treadmill to determine V ˙ O_2peak, VT1, and VT2 using MedGraphics Breezesuit™ software (v-slope). Participants performed an on-ice repeated shift (RSA) test consisting of 8-maximal skating bouts, lasting approximately 25 s and interspersed with 90 s of passive recovery, to determine first gate, second gate, and total sprint decrement (%_dec). Pearson product-moment correlations and multiple regressions were used to assess relationships between ventilatory threshold variables (VT1, VT2, Stage at VT1, and Stage at VT2) and RSA (first gate, second gate, and total course decrement).

Results

Stage at VT2 was the only variable substantially correlated with first gate (r = -0.35; P < 0.05), second gate (r = -0.58; P < 0.001) and total course decrement (r = -0.42; P < 0.05).

Conclusion

The results of this study demonstrated that VT is substantially associated with RSA, and VT2 is more strongly correlated with RSA than V ˙ O_2peak. This study suggests that longer duration high-intensity interval training at intensities that increase workrate at VT2 may lead to possible improvements in RSA.

Exercise as 'precision medicine' for insulin resistance and its progression to type 2 diabetes: a research review

Type 2 diabetes and obesity epidemics are in effect in the United States and the two pathologies are linked. In accordance with the growing appreciation that ‘exercise is medicine,’ it is intuitive to suggest that exercise can play an important role in the prevention and/or treatment of these conditions. However, if exercise is to truly be considered as a viable alternative to conventional healthcare prevention/treatment strategies involving pharmaceuticals, it must be prescribed with similar scrutiny. Indeed, it seems reasonable to posit that the recent initiative calling for ‘precision medicine’ in the US standard healthcare system should also be applied in the exercise setting. In this narrative review, we consider a number of explanations that have been forwarded regarding the pathological progression to type 2 diabetes both with and without the concurrent influence of overweight/obesity. Our goal is to provide insight regarding exercise strategies that might be useful as ‘precision medicine’ to prevent/treat this disease. Although the etiology of type 2 diabetes is complex and cause/consequence characteristics of associated dysfunctions have been debated, it is well established that impaired insulin action plays a critical early role. Consequently, an exercise strategy to prevent/treat this disease should be geared toward improving insulin sensitivity both from an acute and chronic standpoint. However, research suggests that a chronic improvement in insulin sensitivity only manifests when weight loss accompanies an exercise intervention. This has resonance because ectopic fat accumulation appears to represent a central component of disease progression regardless of whether obesity is also part of the equation. The cause/consequence characteristics of the relationship between insulin resistance, pathological fat deposition and/or mobilsation, elevated and/or poorly-distributed lipid within myocytes and an impaired capacity to use lipid as fuel remains to be clarified as does the role of muscle mitochondria in the metabolic decline. Until these issues are resolved, a multidimensional exercise strategy (e.g., aerobic exercise at a range of intensities and resistance training for muscular hypertrophy) could provide the best alternative for prevention/treatment.

Changes in Metabolic Syndrome Severity Following Individualized Versus Standardized Exercise Prescription: A Feasibility Study

This study sought to investigate the efficacy of standardized versus individualized exercise intensity prescription on metabolic syndrome (MetS) severity following a 12-week exercise intervention. A total of 38 experimental participants (47.8 ± 12.2 yr, 170.7 ± 8.0 cm, 82.6 ± 18.7 kg, 26.9 ± 6.7 mL·k⁻¹·min⁻¹) were randomized to one of two exercise interventions (exercise intensity prescribed using heart rate reserve or ventilatory threshold). Following the 12-week intervention, MetS z-score was significantly improved for the standardized (−2.0 ± 3.1 to −2.8 ± 2.8 [p = 0.01]) and individualized (−3.3 ± 2.3 to −3.9 ± 2.2 [p = 0.04]) groups. When separating participants based on prevalence of MetS at baseline and MetS z-score responsiveness, there were six and three participants in the standardized and individualized groups, respectively, with three or more MetS risk factors. Of the six participants in the standardized group, 83% (5/6) of the participants were considered responders, whereas 100% (3/3) of the individualized participants were responders. Furthermore, only 17% (1/6) of the participants with MetS at baseline in the standardized group no longer had symptoms of MetS following the intervention. In the individualized group, 67% (2/3) of participants with baseline MetS were not considered to have MetS at week 12. These findings suggest that an individualized approach to the exercise intensity prescription may ameliorate the severity of MetS.

A "Blood Relationship" Between the Overlooked Minimum Lactate Equivalent and Maximal Lactate Steady State in Trained Runners. Back to the Old Days?

Maximal Lactate Steady State (MLSS) and Lactate Threshold (LT) are physiologically-related and fundamental concepts within the sports and exercise sciences. Literature supporting their relationship, however, is scarce. Among the recognized LTs, we were particularly interested in the disused “Minimum Lactate Equivalent” (LE_min), first described in the early 1980s. We hypothesized that velocity at LT, conceptually comprehended as in the old days (LE_min), could predict velocity at MLSS (_VMLSS) more accurate than some other blood lactate-related thresholds (BL_RTs) routinely used nowadays by many sport science practitioners. Thirteen male endurance-trained [_VMLSS 15.0 ± 1.1 km·h⁻¹; maximal oxygen uptake (V.O2max) 67.6 ± 4.1 ml·kg⁻¹·min⁻¹] homogeneous (coefficient of variation: ≈7%) runners conducted 1) a submaximal discontinuous incremental running test to determine several BL_RTs followed by a maximal ramp incremental running test for V.O2max determination, and 2) several (4–5) constant velocity running tests to determine _VMLSS with a precision of 0.20 km·h⁻¹. Determined BL_RTs include LE_min and LE_min-related LE_min plus 1 (LE_min+1mM) and 1.5 mmol·L⁻¹ (LE_min+1.5mM), along with well-established BL_RTs such as conventionally-calculated LT, D_max and fixed blood lactate concentration thresholds. LE_min did not differ from LT (P = 0.71; ES: 0.08) and was 27% lower than MLSS (P < 0.001; ES: 3.54). LE_min+1mM was not different from MLSS (P = 0.47; ES: 0.09). LE_min was the best predictor of _VMLSS (r = 0.91; P < 0.001; SEE = 0.47 km·h⁻¹), followed by LE_min+1mM (r = 0.86; P < 0.001; SEE = 0.58 km·h⁻¹) and LE_min+1.5mM (r = 0.84; P < 0.001; SEE = 0.86 km·h⁻¹). There was no statistical difference between MLSS and estimated MLSS using LE_min prediction formula (P = 0.99; ES: 0.001). Mean bias and limits of agreement were 0.00 ± 0.45 km·h⁻¹ and ±0.89 km·h⁻¹. Additionally, LE_min, LE_min+1mM and LE_min+1.5mM were the best predictors of V.O2max (r = 0.72–0.79; P < 0.001). These results support LE_min, an objective submaximal overlooked and underused BL_RT, to be one of the best single MLSS predictors in endurance trained runners. Our study advocates factors controlling LE_min to be shared, at least partly, with those controlling MLSS.

Change in VO2max and time trial performance in response to high-intensity interval training prescribed using ventilatory threshold

Completion of high-intensity interval training (HIIT) leads to significant increases in maximal oxygen uptake (VO_2max) and oxidative capacity. However, individual responses to HIIT have been identified as approximately 20-40% of individuals show no change in VO_2max, which may be due to the relatively homogeneous approach to implementing HIIT.

PURPOSE

This study tested the effects of HIIT prescribed using ventilatory threshold (VT) on changes in VO_2max and cycling performance.

METHODS

Fourteen active men and women (age and VO_2max = 27 ± 8 year and 38 ± 4 mL/kg/min) underwent nine sessions of HIIT, and 14 additional men and women (age and VO_2max = 22 ± 3 year and 40 ± 5 mL/kg/min) served as controls. Training was performed on a cycle ergometer at a work rate equal to 130%VT and consisted of eight to ten 1 min bouts interspersed with 75 s of recovery. At baseline and post-testing, they completed progressive cycling to exhaustion to determine VO_2max, and on a separate day, a 5 mile cycling time trial.

RESULTS

Compared to the control group, HIIT led to significant increases in VO_2max (6%, p = 0.007), cycling performance (2.5%, p = 0.003), and absolute VT (9 W, p = 0.005). However, only 57% of participants revealed meaningful increases in VO_2max and cycling performance in response to training, and two showed no change in either outcome.

CONCLUSIONS

A greater volume of HIIT may be needed to maximize the training response for all individuals.

Personalizing physical exercise in a computational model of fuel homeostasis

The beneficial effects of physical activity for the prevention and management of several chronic diseases are widely recognized. Mathematical modeling of the effects of physical exercise in body metabolism and in particular its influence on the control of glucose homeostasis is of primary importance in the development of eHealth monitoring devices for a personalized medicine. Nonetheless, to date only a few mathematical models have been aiming at this specific purpose. We have developed a whole-body computational model of the effects on metabolic homeostasis of a bout of physical exercise. Built upon an existing model, it allows to detail better both subjects' characteristics and physical exercise, thus determining to a greater extent the dynamics of the hormones and the metabolites considered.

On-field prediction vs monitoring of aerobic capacity markers using submaximal lactate and heart rate measures

This study aimed to validate the use of a single blood lactate concentration measurement taken following a 5-minute running bout at 10 km·h^-1 (BLC₁₀ ) and the speed associated with 90% of maximal heart rate (S₉₀ ) to predict and monitor fixed blood lactate concentration (FBLC) thresholds in athletes. Three complementary studies were undertaken. Study I: A cross-sectional study examining the associations of BLC₁₀ and S₉₀ with running speeds at FBLC of 3 (S3mM) and 4 mmol·L^-1 (S4mM) in 100 athletes. Study II: A cross-validation study assessing the predictive capacity of BLC₁₀ and S₉₀ to estimate FBLC thresholds in real practice. Study III: A longitudinal study examining whether training-induced changes in FBLC thresholds could be monitored using BLC₁₀ and S₉₀ in 80 athletes tested before and after an intensified training period. Study I: BLC₁₀ (r=-.87 to -.89) and S₉₀ (r=.73-.79) were very largely (P<.001) related to FBLC thresholds. Study II: Predictive models yielded robust correlations between estimated and measured FBLC thresholds (r=.75-.91; P<.001). The limits of agreements, however, revealed that prediction of FBLC thresholds could be biased up to 9%-15%. Study III: BLC₁₀ was very largely related to training-induced changes in FBLC thresholds (r=-.72 to -.76; P<.001). Increases in S₉₀ were associated with improvements in FBLC thresholds, but decreases in S₉₀ led to unclear changes in FBLC thresholds. This study supports the use of BLC₁₀ as a simple, low-cost, non-fatiguing, and time-efficient functional variable to monitor, but not predict, FBLC thresholds in athletes. The present results also question the use of S₉₀ to detect declines in endurance performance.

The incidence of training responsiveness to cardiorespiratory fitness and cardiometabolic measurements following individualized and standardized exercise prescription: study protocol for a randomized controlled trial

BACKGROUND

There is individual variability to cardiorespiratory fitness (CRF) training, but the underlying cause is not well understood. Traditionally, a standardized approach to exercise prescription has utilized relative percentages of maximal heart rate, heart rate reserve (HRR), maximal oxygen uptake (VO2max), or VO2 reserve to establish exercise intensity. However, this model fails to take into consideration individual metabolic responses to exercise and may attribute to the variability in training responses. It has been proposed that an individualized approach would take into consideration metabolic responses to exercises to increase responsiveness to training.

METHODS

In this randomized control trial, participants will undergo a 12-week exercise intervention using individualized (ventilatory thresholds) and standardized (HRR) methods to prescribe CRF training intensity. Following the intervention, participants will be categorized as responders or non-responders based on changes in maximal aerobic abilities. Participants who are non-responders will complete a second 12-week intervention in a crossover design to determine whether they can become responders with a differing exercise prescription. There are four main research outcomes: (1) determine the cohort-specific technical error to use in the categorization of response rate; (2) determine if an individualized intensity prescription is superior to a standard approach in regards to VO2max and cardiometabolic risk factors; (3) investigate the time course changes throughout 12 weeks of CRF training between the two intervention groups; and (4) determine if non-responders can become responders if the exercise prescription is modified.

DISCUSSION

The findings from this research will provide evidence on the effectiveness of individualized exercise prescription related to training responsiveness of VO2max and cardiometabolic risk factors compared to a standardized approach and further our understanding of individual exercise responses. If the individualized approach proposed is deemed effective, it may change the way exercise specialists prescribe exercise intensity to enhance training responsiveness.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT02868710 . Registered on 15 August 2016.

Changes in systolic arterial pressure variability are associated with the decreased aerobic performance of rats subjected to physical exercise in the heat

Enhanced cardiovascular strain is one of the factors that explains degraded aerobic capacity in hot environments. The cardiovascular system is regulated by the autonomic nervous system, whose activity can be indirectly evaluated by analyzing heart rate variability (HRV) and systolic arterial pressure (SAP) variability. However, no study has addressed whether HRV or SAP variability can predict aerobic performance during a single bout of exercise. Therefore, this study aimed to investigate whether there is an association between cardiovascular variability and performance in rats subjected to treadmill running at two ambient temperatures. In addition, this study investigated whether the heat-induced changes in cardiovascular variability and reductions in performance are associated with each other. Male Wistar rats were implanted with a catheter into their carotid artery for pulsatile blood pressure recordings. After recovery from surgery, the animals were subjected to incremental-speed exercise until they were fatigued under temperate (25°C) and hot (35°C) conditions. Impaired performance and exaggerated cardiovascular responses were observed in the hot relative to the temperate environment. Significant and negative correlations between most of the SAP variability components (standard deviation, variance, very low frequency [VLF], and low frequency [LF]) at the earlier stages of exercise and total exercise time were observed in both environmental conditions. Furthermore, the heat-induced changes in the sympathetic components of SAP variability (VLF and LF) were associated with heat-induced impairments in performance. Overall, the results indicate that SAP variability at the beginning of exercise predicts the acute performance of rats. Our findings also suggest that heat impairments in aerobic performance are associated with changes in cardiovascular autonomic control.

Determination of exercise training heart rate in patients on β-blockers after myocardial infarction

BACKGROUND

In patients with coronary artery disease, the target intensity-level of exercise training is usually based on a training heart rate that aims to be close to the upper level of metabolic aerobic exercise.

AIM

We intended to evaluate whether a training heart rate calculated with the Karvonen formula after a conventional exercise test is comparable with the heart rate at the anaerobic threshold in patients after myocardial infarction treated with beta-blockers and if not to propose a new formula.

METHODS AND RESULTS

In this multicenter prospective study, 115 consecutive beta-blocked patients recovering from myocardial infarction performed a cardiopulmonary exercise test to determine the anaerobic threshold. The training heart rate determined by the Karvonen formula was compared with the heart rate at the anaerobic threshold in a derivation sample (n=58) and a validation sample (n=57) of patients. The Karvonen training heart rate was significantly lower than the heart rate at the anaerobic threshold (91+/-5 versus 102+/-17 bpm, P<0.0001) in the first sample of patients and this difference was clinically relevant in 40% of patients. Thus, a 'modified Karvonen training heart rate', equal to 0.8xx(maximum heart rate-resting heart rate)+resting heart rate, was calculated by linear regression in the derivation sample and prospectively assessed in the validation sample. The modified Karvonen training heart rate was closer to the heart rate at the anaerobic threshold than the Karvonen training heart rate, and the difference between the modified Karvonen training heart rate and the heart rate at the anaerobic threshold was clinically relevant in only 5% of patients.

CONCLUSION

The Karvonen formula underestimates the heart rate at the anaerobic threshold in beta-blocked patients, which may lead to undertraining of patients with coronary artery disease; we propose another formula more adapted to these patients.

Does cumulating endurance training at the weekends impair training effectiveness?

BACKGROUND

Due to occupational restrictions many people's recreational endurance activities are confined to the weekends. We intended to clarify if cumulating the training load in such a way diminishes endurance gains.

DESIGN

We conducted a longitudinal study comparing training-induced changes within three independent samples.

METHODS

Thirty-eight healthy untrained participants (45+/-8 years, 80+/-18 kg; 172+/-9 cm) were stratified for endurance capacity and sex and randomly assigned to three groups: 'weekend warrior' (n=13, two sessions per week on consecutive days, 75 min each, intensity 90% of the anaerobic threshold; baseline lactate+1.5 mmol/l), regular training (n=12, five sessions per week, 30 min each, same intensity as weekend warrior), and control (n=13, no training). Training was conducted over 12 weeks and monitored by means of heart rate. Identical graded treadmill protocols before and after the training program served for exercise prescription and assessment of endurance effects.

RESULTS

VO2max improved similarly in weekend warrior (+3.4 ml/min per kg) and register training (+1.5 ml/min per kg; P=0.20 between groups). Compared with controls (-1.0 ml/min per kg) this effect was significant for weekend warriors (P<0.01) whereas there was only a tendency for the regular training group (P=0.10). In comparison with controls (mean decrease, 3 beats/min), the average heart rate during exercise decreased significantly by 11 beats/min (weekend warriors, P<0.01) and 9 beats/min (regular training, P<0.05). There was no significant difference, however, between the weekend warrior and regular training groups (P=0.99).

CONCLUSION

In a middle-aged population of healthy untrained subjects, cumulating the training load at the weekends does not lead to an impairment of endurance gains in comparison with a smoother training distribution.