Comparative effects of high-intensity interval training and moderate-intensity continuous training on weight and metabolic health in college students with obesity

The purpose of this study was to compare the effects of High-Intensity Interval Training (HIIT) and Moderate-Intensity Continuous Training (MICT) on weight, body composition, blood lipid indicators, and metabolic status in college students living with obesity. The study focused on a sample of 40 college students living with obesity, including 20 males and 20 females, aged between 18 and 25. Participants were randomly assigned to either the HIIT group or the MICT group. Both groups underwent an 8-week intervention, consisting of three sessions per week with alternate-day training. The MICT group's training consisted of continuous aerobic exercise for 35 min at 60-70% of maximum heart rate. The HIIT group engaged in 28 min of alternating high-intensity and low-intensity exercise, where the high-intensity phase was at 85-90% of maximum heart rate for 4 min, followed by a 3-min recovery period at 50-60% of maximum heart rate, repeated four times. Both groups underwent heart rate monitoring before and after the training sessions to ensure the accuracy of the training intensity. Within each group, further distinctions were made based on gender, resulting in the following subgroups: Male HIIT group (n = 10), Female HIIT group (n = 10), Male MICT group (n = 10), and Female MICT group (n = 10). Differences in anthropometric and biochemical indicators among the groups were analyzed, and the different effects of the two intervention strategies on the obese college student population were comprehensively evaluated. Compared to the baseline assessment, the HIIT group showed a more favorable declining trend than the MICT group in terms of body morphology and body composition, particularly in the aspect of body fat percentage (BF%). The male HIIT group, female HIIT group, male MICT group, and female MICT group respectively reduced by - 23.71%, - 26.76%, - 9.81%, - 7.16%. Male and female HIIT group experienced a more pronounced decrease compared to the MICT group, with the female HIIT group reducing an additional 3.75% more than the male HIIT group. Regarding intergroup differences, BF% significant differences were shown between male MICT group and the HIIT group (P < 0.05), and female MICT group and the HIIT group (P < 0.01). In terms of biochemical indicators, the HIIT group also presented a more favorable declining trend compared to the MICT group, with male HIIT participants showing more reduction than female HIIT participants, especially in total cholesterol (TC) (10.64%), low-density lipoprotein cholesterol (LDL-C) (11.73%), alanine aminotransferase (ALT) (11.99%), and uric acid (UA) (11.76%). Regarding triglycerides (TG), significant intergroup differences were observed between male MICT and HIIT groups (P < 0.01) and female MICT and HIIT groups (P < 0.01). Concerning ALT, a significant difference was shown between female MICT and HIIT groups (P < 0.01), while no significant difference was observed among male participants. Overall, for college students living with obesity, both HIIT and MICT have shown positive effects. Among these, HIIT demonstrates greater effectiveness compared to MICT in BF% and biochemical markers.

Different humidity environments do not affect the subsequent exercise ability of college football players after aerobic high-intensity interval training

Previous studies have explored the effect of differing heat and relative humidity (RH) environments on the performance of multiple anaerobic high-intensity interval training (HIIT). Still, its impact on physiological responses and performance following aerobic HIIT has not been well studied. This study examined the effects of differing RH environments on physiological responses and performance in college football players following HIIT. Twelve college football completed HIIT under four different environmental conditions: (1) 25 °C/20% RH (Control group); (2) 35 °C/20% RH (H20 group); (3) 35 °C/40% RH (H40 group); (4) 35 °C/80% RH (H80 group). The heart rate (HR), mean arterial pressure (MAP), lactate, tympanic temperature (TT), skin temperature (TS), thermal sensation (TS), and rating of perceived exertion (RPE) were recorded continuously throughout the exercise. The heart rate variability (HRV): including root mean squared differences of the standard deviation (RMSSD)、standard deviation differences of the standard deviation (SDNN)、high frequency (HF), low frequency (LF), squat jump height (SJH), cycling time to exhaustion (TTE), and sweat rate (SR) were monitored pre-exercise and post-exercise. The HR, MAP, lactate, TT, Ts, TS, and RPE in the 4 groups showed a trend of rapid increase, then decreased gradually. There was no significant difference in HR, MAP, TT, or RPE between the 4 groups at the same time point (p > 0.05), in addition to this, when compared to the C group, the lactate, Ts, TS in the other 3 groups significant differences were observed at the corresponding time points (p < 0.05). The RMSSD, SDNN, HF, and LF levels in the 4 groups before exercise were not significantly different. The RMSSD and HF in the H40 and H80 groups were significantly decreased and other HRV indicators showed no significant difference after exercise. In sports performance measurement, the SJH and TTE were significantly decreased, but there was no significant difference in the 4 groups. The SR was no significant difference in the 4 groups after exercise. In conclusion, heat and humidity environments elicited generally greater physiological effects compared with the normal environment but did not affect sports performance in college football players.

High-intensity interval training improves bone remodeling, lipid profile, and physical function in multiple sclerosis patients

Multiple sclerosis (MS) is a demyelinating and neurodegenerative disease due to an autoimmune chronic inflammatory response, yet the etiology is currently not completely understood. It is already known that physical activity plays an essential role in improving quality of life, especially in neuropathological conditions. The study was aimed to investigate the possible benefits of high-intensity interval training (HIIT) in bone and lipid metabolism markers, and neuromotor abilities in MS patients. 130 participants were recruited; 16 subjects with MS met the inclusion criteria and were included in the data analysis. The patients were randomly assigned to two groups: a Control group (CG) (34.88 ± 4.45 yrs) that didn't perform any physical activity and the Exercise group (EG) (36.20 ± 7.80 yrs) that performed HIIT protocol. The training program was conducted remotely by a kinesiologist. It was performed three times a week for 8 weeks. At the beginning (T0) and the end of the study (T1) physical function tests, bone remodelling markers, and lipid markers analyses were performed. After 8 weeks of training the wall squat (s) (T0 = 27.18  ±  4.21; T1 = 41.68 ± 5.38, p ≤ 0.01) and Time Up and Go test (s) (T0 = 7.65 ± 0.43; T1 = 6.34 ± 0.38 p ≤ 0.01) performances improved; lipid markers analysis showed a decrease in Total (mg/dl) (T0 = 187.22 ± 15.73; T1 = 173.44 ± 13.03, p ≤ 0.05) and LDL (mg/dl) (T0 = 108 ± 21.08; T1 = 95.02 ± 17.99, p < 0.05) cholesterol levels. Additionally, the levels of osteocalcin (µg/L), a marker of bone formation increased (T0 = 20.88 ± 4.22; T1 = 23.66 ± 6.24, p < 0.05), 25-OH Vitamin D (µg/L) improved after 8 weeks (T0 = 21.11 ± 7.11; T1 = 27.66 ± 7.59, p < 0.05). HIIT had an effect on lower limb strength and gait control, improved bone formation, and lipid management, in MS patients.

Five-year follow-up of the OptiTrain trial on concurrent resistance and high-intensity interval training during chemotherapy for patients with breast cancer

The protocol predefined aim of this study is to assess sustained effects of the OptiTrain trial on several health outcomes, 5 years after the baseline assessment. The OptiTrain study was a prospective, randomised controlled trial with 240 patients with breast cancer undergoing adjuvant chemotherapy that compared the effects of 16 weeks of two exercise programs, RT-HIIT and AT-HIIT, with usual care (UC). After a 5-year follow-up, eligible participants were evaluated for the primary outcome of cancer-related fatigue (CRF) and secondary outcomes including quality of life, symptoms, muscle strength, cardiorespiratory fitness, body mass, physical activity, and sedentary behavior. Statistical analysis was conducted using linear mixed models adjusted for baseline values. Tumour profile and menopausal status were additionally adjusted for CRF. Mean differences (MD), 95% confidence intervals (CIs), and standardized effect sizes (ES) were reported. At the 5-year follow-up, there were no statistically significant differences in total CRF between the intervention groups and the UC group. RT-HIIT reported significantly reduced pain sensitivity at the gluteus MD = 79.00 (95% CI 10.17, 147.83, ES = 0.55) compared to UC. Clinically meaningful differences for an increase in cognitive CRF and cardiorespiratory fitness were observed for the AT-HIIT versus UC group, and for lower limb strength for the RT-HIIT versus UC group, albeit without statistical significance. Engaging in targeted exercise during adjuvant chemotherapy for breast cancer provides short-term benefits in reducing fatigue and maintaining physical function. However, our 5-year follow-up indicates that these effects are limited in the long term. This underscores the need to support breast cancer survivors maintain their PA levels throughout their survivorship journey.

High-Intensity Interval Versus Moderate-Intensity Continuous Exercise Training on Glycemic Control, Beta Cell Function, and Aerobic Fitness in Women with Type 2 Diabetes

Objective: This study aimed to compare the effects of High-Intensity Interval Training (HIIT) and Moderate-Intensity Continuous Training (MICT) on glycemic control, beta-cell function, and aerobic fitness in women with Type 2 Diabetes Mellitus (T2DM). Methods: Thirty-six women with T2DM were assigned equally to HIIT, MICT, and control (CON) groups. Participants in the exercise cohorts underwent a 12-week training regimen (three sessions per week), while the CON group maintained an inactive lifestyle. Glycaemia variables, beta-cell function, maximal oxygen uptake (VO2max), lipid profiles, and body composition were assessed at baseline and post-intervention. Results: Both HIIT and MICT interventions led to significant improvements in glucose, insulin, HbA1c, and insulin resistance index. Moreover, visceral adiposity index (VAI), lipid accumulation product (LAP), total cholesterol (TC), and low-density lipoprotein (LDL) levels significantly decreased in the HIIT and MICT groups after 12 weeks. Triglyceride (TG) levels decreased only after MICT, while high-density lipoprotein (HDL) levels increased after both interventions. Maximal oxygen uptake (VO2max), body mass, body mass index (BMI), and waist circumference (WC) significantly improved in all exercise groups. Notably, the HIIT group showed greater reductions in body mass compared to MICT. Nevertheless, beta-cell function remained unaltered after these two exercise regimens. Conclusion: Both HIIT and MICT interventions effectively managed T2DM in women, regardless of exercise intensity. The HIIT regimen can be considered for time-efficient lifestyle interventions in people with T2DM.

Moderate-intensity continuous training and high-intensity interval training modulate the composition of the oral microbiota of elderly adults: Randomized controlled trial

OBJECTIVE

We investigates the effects of 16-week high-intensity interval training and moderate-intensity continuous training on the composition of the oral microbiota. To the best of our knowledge, at the time of writing this paper no other scholars had described the oral metagenomic changes associated with prescribed exercise in older adults.

METHODS

Forty-three participants aged 60-74 years were randomized 1:1:1 to a control group, high-intensity interval training or moderate-intensity continuous training twice weekly for 16 weeks. Saliva samples were sequenced at baseline, week 8 and week 16 of intervention.

RESULTS

High-intensity interval training produced significant differences over time in Richness and a clear trend to decreased Simpson and Shannon diversity indices. In contrast, Simpson and Shannon indices showed an upward trend over time with moderate-intensity continuous training, which also decreased Firmicutes and increased Bacteroidetes levels. Significant differences in the abundance of pathogenic species were also observed after the participants completed the exercise interventions of either type.

CONCLUSIONS

Both types of exercise promoted subtle changes in the oral microbiota, confirming the modulatory effect of high-intensity interval training and moderate-intensity continuous training on the oral microbiome. Clinical trial registration NCT05220670.

A narrative review exploring advances in interval training for endurance athletes

Interval training is considered an essential training component in endurance athletes. Recently, there has been a focus on optimization of interval training characteristics to sustain a high fraction of maximal oxygen consumption (≥90% VO2max) to improve physiological adaptations and performance. Herein, we present a synopsis of the latest research exploring both acute and chronic studies in endurance athletes. Further, a decision flowchart was created for athletes and coaches to select the most appropriate interval training regime for specific individualized goals.

The 40-min HIIT acutely induced bone formation which was likely through the increases in muscle derived interleukin 6 and adiponectin activation: The 16 weeks of HIIT intervention, longitudinal randomized controlled trial

PURPOSE

There is some controversy regarding cytokines released from adipocytes, particularly adiponectin, leptin, and IL6 that regulate bone remodeling. In addition, IL6 is released from muscle contraction, which might have a distinct role in bone remodeling. Hence, this study investigated whether muscle contraction during a session of 40 min of high intensity interval training (40-min HIIT) and after 16 weeks of HIIT (16-wk HIIT) altered the release of those cytokines and bone remodeling in overweight women.

METHODS

In total, 22 overweight, premenopausal women were randomly assigned to either the exercise or the control group. The exercise participants engaged in the 40-min HIIT session at 80-90 % of their heart rate reserve (HRR) three times weekly for 16 weeks, while the control participants performed their routine daily activities. Blood was drawn after overnight fasting and immediately after completing the 40-min HIIT sessions to investigate the association of adiponectin, leptin, IL6, CTX, and P1NP through the acute effect of the 40-min HIIT sessions. This process was repeated after the 16-wk intervention program to observe the training effect of HIIT on cytokines linkage. The bone mineral density (BMD) levels of the distal tibia, femur, and lumbar spine were determined prior to and after the 16-wk intervention using dual-energy X-ray absorptiometry.

RESULTS

The P1NP level increased by 8.29-20.52 % (95 % CI) and by 2.91-15.54 % after completing the first and last bouts of the 40-min HIIT sessions, respectively. In addition, IL6 increased by 13.39-28.03 % (95 % CI), while serum CTX and adiponectin were unaltered from the acute effect of the 40-min HIIT sessions. There was an association between the increases in P1NP and adiponectin (r = 0.682, p = 0.015); however, the increase in P1NP was mostly associated with the increase in IL6 (r = 0.572, p = 0.054) after completing a 40-min HIIT session. After the 16-wk HIIT program, the resting adiponectin level of the exercise participants increased; however, this was associated with neither bone biomarkers nor BMD. The BMDs of the exercise participants were maintained; however, the tibial BMD of the control participants decreased with an increase in the resting CTX level after 16 weeks.

CONCLUSION

Muscle contraction during the 40-min HIIT session elevated the IL6 level, which might have subsequently enhanced bone formation. Furthermore, the association between acute changes in adiponectin and P1NP suggested the possibility of an increase in the sensitivity of the adiponectin receptor in osteoblasts.

Blood pressure and heart rate variability to assess autonomic response to an acute bout of high intensity interval exercise in healthy young adults

Autonomic nervous system (ANS) activity causes acute variations in blood pressure (BP) and heart rate (HR). These systems are challenged during high intensity interval exercise (HIIE). However, BP variability (BPV) and HR variability (HRV) response to HIIE is unknown. We characterized BPV and HRV during an acute HIIE bout using spectral low frequency [LF] and high frequency [HF] domains. We hypothesized that BPV would increase and HRV would decrease during high-intensity and active-recovery of HIIE compared to baseline [BL] and BPV would reduce and HRV would increase during cool down, post-HIIE, and 30 min post-HIIE compared to BL. HIIE involved 10 min of alternating high-intensity and active-recovery (approximately 70% and 10% of Wattmax) on a recumbent stepper. We did a secondary analysis on 23 datasets. The participants were 25 ± 1.5 years, 48% females. Our results showed high-intensity BPV LF was not significantly different from BL while HF increased. HRV LF and HF decreased compared to BL. During active-recovery, LF and HF for BPV and HRV increased greater than high-intensity. HRV LF and HF returned to BL after 30 min of recovery, whereas BPV HF was higher compared to BL. The rapid switching during HIIE uniquely modulates cardiovascular and ANS.

HIIT at Home: Enhancing Cardiorespiratory Fitness in Older Adults-A Randomized Controlled Trial

BACKGROUND

This study aimed to investigate the effectiveness of a 6-month home-based high-intensity interval training (HIIT) intervention to improve peak oxygen consumption (V̇O2peak) and lactate threshold (LT) in older adults.

METHODS

Two hundred thirty-three healthy older adults (60-84 years; 54% females) were randomly assigned to either 6-month, thrice-weekly home-based HIIT (once-weekly circuit training and twice-weekly interval training) or a passive control group. Exercise sessions were monitored using a Polar watch and a logbook for objective and subjective data, respectively, and guided by a personal coach. The outcomes were assessed using a modified Balke protocol combining V̇O2peak and LT measures. General linear regression models assessed between-group differences in change and within-group changes for each outcome.

RESULTS

There was a significant between-group difference in the pre-to-post change in V̇O2peak (difference: 1.8 [1.2; 2.3] mL/kg/min; exercise: +1.4 [1.0; 1.7] mL/kg/min [~5%]; control: -0.4 [-0.8; -0.0] mL/kg/min [approximately -1.5%]; effect size [ES]: 0.35). Compared with controls, the exercise group had lower blood lactate concentration (-0.7 [-0.9; -0.4] mmol/L, ES: 0.61), % of peak heart rate (-4.4 [-5.7; -3.0], ES: 0.64), and % of V̇O2peak (-4.5 [-6.1; -2.9], ES: 0.60) at the intensity corresponding to preintervention LT and achieved a higher treadmill stage (% incline) at LT (0.6 [0.3; 0.8]; ES: 0.47), following the intervention.

CONCLUSION

This study highlights the effectiveness of a home-based HIIT intervention as an accessible and equipment-minimal strategy to induce clinically meaningful improvements in cardiorespiratory fitness in older adults. Over 6 months, the exercise group showed larger improvements in all outcomes compared with the control group. Notably, the LT outcome exhibited a more pronounced magnitude of change than V̇O2peak.

Effects of Different Recovery Periods Following a Very Intense Interval Training Session on Strength and Explosive Performance in Elite Female Ice Hockey Players

ABSTRACT

Petré, H, Tinmark, F, Rosdahl, H, and Psilander, N. Effects of different recovery periods following a very intense interval training session on strength and explosive performance in elite female ice hockey players. J Strength Cond Res 38(7): e383-e390, 2024-This study investigates how different recovery periods after high-intensity interval training (HIIT) affects strength and explosive performance during a power training (PT) session. Fifteen female elite ice hockey players (22.5 ± 5.2 years) performed PT, including 6 sets of 2 repetitions (reps) of isometric leg press (ILP) and 6 sets of 3 reps of countermovement jump (CMJ), following a rested state and 10 minutes, 6 hours, or 24 hours after HIIT (3 sets of 8 × 20 seconds at 115% of power output at maximal oxygen consumption on a cycle ergometer). Peak force (PF) and peak rate of force development (pRFD) were measured during the ILP. Peak jump height (PJH), concentric phase duration (ConDur), eccentric phase duration, total duration, peak power (PP), velocity at peak power (V@PP), and force at peak power were measured during CMJ. The following variables were significantly reduced when only a 10-minute recovery period was allowed between HIIT and PT: PF was reduced by 7% ( p < 0.001), pRFD by 17% ( p < 0.001), PJH by 4% ( p < 0.001), ConDur by 4% ( p = 0.018), PP by 2% ( p = 0.016), and V@PP by 2% ( p = 0.007). None of the measured variables were reduced when PT was performed 6 and 24 hours after HIIT. We conclude that strength and explosive performance of elite female ice hockey players is reduced 10 minutes after HIIT but not negatively affected if a rest period of at least 6 hours is provided between HIIT and PT.

Investigating the Alcohol Effects on the Response to Strenuous Exercise Training: Protocol for a Multidisciplinary Intervention Study in Young Healthy Adults-The BEER-HIIT Study

High-intensity interval training (HIIT) is a time-efficient strategy to improve fitness and performance. Whereas the multiple and negative effects of high intake of alcohol have been widely studied, the effect of moderate alcohol doses after exercise is not clear, and it is currently under debate. For that, a total of 80 young healthy adults are studied and allocated into 5 groups, each including 16 participants. Four groups follow a HIIT program, while the fifth group is a control non-training group. The training groups will be randomized according to the characteristics of the ingested beverage (alcohol beer, beer 0.0%, sparkling water, or ethanol). The effects of HIIT on several aspects of physical performance and mental health in young healthy adults are evaluated, also the concomitant effect of daily and moderate alcohol consumption. The novelty of this study lies in the continuous measurement of the psychological parameters associated with carrying out a highly demanding training program in conjunction with alcohol consumption in moderate quantities, reflecting real-life conditions.

Warm-up plus verbal communications administered as placebo procedure during the training session improves running performance

The aim of this study was to investigate the effects on running performance of a within-session placebo procedure consisting of a conditioning treatment plus verbal communications. Twenty-six subjects were assigned to PLACEBO and CONTROL groups. Participants performed three sessions: Session 1-Cooper Test, Session 2-Baseline session and Session 3-Experimental session. During Session 2, participants performed a sprint-interval-training (SIT)-until-exhaustion preceded by a general warm-up, while in Session3 the SIT was preceded by a conditioning treatment (FIFA11+ warm-up), known to be effective in preventing injuries but not improving performance. Moreover, in Session3, only the PLACEBO group received verbal suggestions (before the warm-up) to influence participants' expectations about FIFA11+ effectiveness in improving performance, and deceptive feedback (during each SIT recovery bout) to increase the conditioning effect. To evaluate performance improvements, Running Time was chosen as a main outcome while to ensure participants reached exhaustion, physiological and metabolic responses were monitored. Total running distance (TRD) was also measured. Results showed that, Running Time and TRD significantly increased in the PLACEBO group whilst no differences in the CONTROL group were observed thus, suggesting the effectiveness of the within-session-placebo procedure in improving running performance. These findings shed a new light on the interaction between cognitive domain and performance, thus encouraging coaches to adopt this innovative method during the training protocol to enhance athletes' performance. Moreover, this placebo procedure, not requiring additional time, tools or resources, could represent a more ecological approach that can be easily adopted in the field.

Physiological and Metabolic Responses to Low-Volume Sprint Interval Exercises: Influence of Sprint Duration and Repetitions

PURPOSE

This study aimed to determine physiological and metabolic responses to two different sprint interval exercises (SIE) matched for total sprint duration and sprint-rest ratio.

METHODS

After having measured peak oxygen uptake (V̇O 2peak ), 14 healthy males (27.1 ± 4.8 yr, 169.6 ± 6.0 cm, 64.5 ± 8.4 kg, V̇O 2peak : 47.2 ± 7.7 mL·kg -1 ·min -1 ) performed four 10-s sprints with 80-s recovery (SIE10) and two 20-s sprints with 160-s recovery (SIE20) on different occasions in a counterbalanced crossover manner. Pulmonary V̇O 2 and changes in tissue oxygenation index (∆TOI) at vastus lateralis (VL) and rectus femoris (RF) were measured during the SIE. Furthermore, T2-weighted magnetic resonance imaging was taken immediately before and after the SIE to determine the activation levels of VL, RF, vastus medialis, vastus intermedius, adductor magnus, biceps femoris long head, semitendinosus, and semimembranosus at 50% of right thigh length.

RESULTS

In SIE10, increases in V̇O 2 and ∆TOI at VL and RF plateaued after the second sprint, whereas session-averaged ∆TOI was greater in SIE20 than SIE10 in both muscles (VL: 20.9 ± 7.4 vs 14.2% ± 5.9%, RF: 22.8 ± 9.3 vs 12.9% ± 6.6%, P = 0.00). Although both SIE significantly increased T2 values in all eight muscles, those magnitudes were similar between the conditions (SIE10 vs SIE20: 5%-16% vs 8%-16%).

CONCLUSIONS

This study showed blunted responses of whole-body (V̇O 2 ) and peripheral (∆TOI) oxidative responses with successive sprints (sprint 1 < sprints 2-4) in SIE10, suggesting that increasing sprint repetitions does not necessarily induce greater oxidative metabolism or stimulus. Moreover, greater peripheral oxygen extraction (∆TOI) was achieved with SIE20, whereas %changes of T2 indicates that the thigh muscles were similarly activated between the SIE conditions.

A Worksite Intervention Program for Obese Sedentary Women Using Wearable Technology

BACKGROUND

The sedentary aspects of work have been associated with increased health risks. The purpose of this study was to compare the effects of high intensity interval training (HIIT) and increased steps on anthropometric, body mass, and body composition changes over a 12-week period.

METHODS

12 sedentary, obese, body mass index (BMI) = 32.98 ± 3.21 kg/m2, adult (46.10 ± 9.56 years), females volunteered for the study and were randomly assigned into one of the two groups, the HIIT group and the STEP group. During the 12-week study, all participants' movements were monitored during their workday, via an accelerometer, a Movband™, 5 days/week.

FINDINGS

The HIIT group (n = 5) engaged in structured exercise (~15.0 ± 3.5 minutes), defined as total body moves which consisted of eight different routines: upper and lower extremity, two cardio segments, two total body, yoga, and abdominal exercises. The STEP group (n = 7) averaged ~7,000 steps/day throughout 12 weeks. Pre- and post-program measurements included: five anthropometric measurements (biceps, waist, abdomen, hips, and thigh), along with body mass and body composition measures: relative (%) body fat via dual x-ray absorptiometry (DEXA) scan, fat mass, fat-free mass, and lean mass.

CONCLUSIONS

Statistical significance was determined among participants for biceps, hips, and thigh measurements along with body mass and body composition changes for improved health.

APPLICATION TO PRACTICE

This work is suggestive that a physical activity intervention integrated into the workplace via work processes and/or structured exercise is supportive in reducing anthropometric and body composition measurements, while changing body mass, to increase health and reduce obesity-related chronic disease risks in sedentary women.

Reduced-exertion high-intensity interval training (REHIT): a feasible approach for improving health and fitness?

In recent years, research investigating the dose-response to sprint interval training (SIT) has provided evidence that the number and duration of repetitions in a SIT session can be reduced whilst preserving the beneficial health-related adaptations. Together this research has led to the development of protocols involving minimal doses of SIT: regularly performing just two or three 20-30 s all-out sprints in a 10 min training session has been shown to elicit beneficial metabolic and cardiovascular adaptations. These SIT protocols, which we originally termed "reduced-exertion high-intensity interval training" (or REHIT), have the potential to remove many of the common barriers associated with other SIT protocols, as well as with HIT and aerobic exercise. Here, we critically review the evidence on the efficacy, feasibility and acceptability, and effectiveness of REHIT for improving health and fitness.

People with obesity exhibit losses in muscle proteostasis that are partly improved by exercise training

This pilot experiment examines if a loss in muscle proteostasis occurs in people with obesity and whether endurance exercise positively influences either the abundance profile or turnover rate of proteins in this population. Men with (n = 3) or without (n = 4) obesity were recruited and underwent a 14-d measurement protocol of daily deuterium oxide (D2O) consumption and serial biopsies of vastus lateralis muscle. Men with obesity then completed 10-weeks of high-intensity interval training (HIIT), encompassing 3 sessions per week of cycle ergometer exercise with 1 min intervals at 100% maximum aerobic power interspersed by 1 min recovery periods. The number of intervals per session progressed from 4 to 8, and during weeks 8-10 the 14-d measurement protocol was repeated. Proteomic analysis detected 352 differences (p < 0.05, false discovery rate < 5%) in protein abundance and 19 (p < 0.05) differences in protein turnover, including components of the ubiquitin-proteasome system. HIIT altered the abundance of 53 proteins and increased the turnover rate of 22 proteins (p < 0.05) and tended to benefit proteostasis by increasing muscle protein turnover rates. Obesity and insulin resistance are associated with compromised muscle proteostasis, which may be partially restored by endurance exercise.

The effects of affect-guided interval training on pleasure, enjoyment, and autonomy: A registered report

This registered report tested the effects of a novel exercise protocol, namely affect-guided interval training, on motivationally relevant variables of remembered pleasure, forecasted pleasure, enjoyment, and autonomy. Affect-guided interval training (AIT) consisted of 60-s intervals that alternated between the highest pleasant intensity and lowest pleasant intensity for 20 min; this was intended to minimize the potential displeasure of traditional high-intensity interval training. The novel protocol was compared to self-selected exercise intensity (30 min) and high-intensity interval training (60-s intervals for 20 min). All sessions were, on average, vigorous in intensity (80-89% peak heart rate). Data indicate that the AIT session was experienced as the most pleasant, had the most pleasant slope of affect, was remembered as the most pleasant, resulted in the most positive affective forecasts, and was the most enjoyable. Both the affect-guided interval session and self-selected exercise session resulted in greater autonomy than high-intensity interval training. Several evaluative and motivationally relevant variables, including (a) remembered pleasure, (b) enjoyment, and (c) forecasted pleasure were predicted by (a) experienced pleasure, the (b) pleasure experienced at the end of exercise, and (c) the slope of pleasure experienced throughout the exercise session. Overall, this study suggests that affect-guided interval training is a feasible and positive alternative that can be included as a viable option for exercise programming.

Applicability of a supramaximal high-intensity interval training program for older adults previously not engaged in regular exercise; analyses of secondary outcomes from the Umeå HIT Study

This analysis of secondary outcomes investigated the applicability of supramaximal high-intensity interval training (HIT) with individually prescribed external intensity performed on stationary bicycles. Sixty-eight participants with a median (min; max) age of 69 (66; 79), at the time not engaged in regular exercise were randomized to 25 twice-weekly sessions of supramaximal HIT (20-min session with 10 × 6-s intervals) or moderate-intensity training (MIT, 40-min session with 3 × 8-min intervals). The primary aim was outcomes on applicability regarding; adherence to prescribed external interval intensity, participant reported positive and negative events, ratings of perceived exertion (RPE 6-20), and affective state (Feeling Scale, FS -5-5). A secondary aim was to investigate change in exercise-related self-efficacy (Exercise Self-Efficacy Scale) and motivation (Behavioural Regulations in Exercise Questionnaire-2). Total adherence to the prescribed external interval intensity was [median (min; max)] 89 % (56; 100 %) in supramaximal HIT, and 100 % (95; 100 %) in MIT. The supramaximal HIT group reported 60 % of the positive (112 of 186) and 36 % of the negative (52 of 146) events. At the end of the training period, the median (min; max) session RPE was 15 (12; 17) for supramaximal HIT and 14 (9; 15) for MIT. As for FS, the median last within-session rating was 3 (-1; 5) for supramaximal HIT and 3 (1; 5) for MIT. Exercise-related motivation increased (mean difference in Relative Autonomy Index score = 1.54, 95 % CI [0.69; 2.40]), while self-efficacy did not change (mean difference = 0.55, 95 % CI [-0.75; 1.82]), regardless of group. This study provide support for supramaximal HIT in supervised group settings for older adults.

Acute Intermittent Hypoxia With High-Intensity Gait Training in Chronic Stroke: A Phase II Randomized Crossover Trial

BACKGROUND

Studies in individuals with chronic stroke indicate high-intensity training (HIT) focused on walking improves locomotor function, which may be due to repeated activation of locomotor circuits and serotonin-dependent modulation of motor output. Separate studies in animals and individuals with spinal cord injury suggest acute intermittent hypoxia (AIH) can augment the effects of locomotor interventions through similar serotonin-dependent mechanisms, although no studies have coupled AIH with HIT in individuals poststroke. The goal of this study was to evaluate the safety and efficacy of AIH+HIT versus HIT alone in individuals with chronic stroke.

METHODS

This phase II double-blind randomized, crossover trial recruited individuals between 18 and 85 years old, >6 months poststroke, and self-selected speeds <1.0 m/s. Participants received up to 15 sessions of AIH for 30 minutes using 15 cycles of hypoxia (60-90 seconds; 8%-9% O2) and normoxia (30-60 seconds; 21% O2), followed by 1 hour of HIT targeting >75% heart rate reserve. The control condition received normoxia for 30 minutes before HIT. Following the first training phase, participants performed the second phase >1 month later. The primary outcomes were self-selected speed and fastest speed, a 6-minute walk test, and peak treadmill speed. A 3-way mixed-model ANOVA assessed the effects of time, training, and order of interventions.

RESULTS

Of 55 individuals screened, 35 were randomized to AIH+HIT or normoxia+HIT first, and 28 individuals completed both interventions, revealing greater gains in self-selected speeds (0.14 [0.08-0.18] versus 0.05 [0.01-0.10] m/s), fastest speed (0.16 [0.10-0.21] versus 0.06 [0.02-0.10] m/s), and peak treadmill speed (0.21 [0.14-0.29] versus 0.11 [0.06-0.16] m/s) following AIH+HIT versus normoxia+HIT (P<0.01) with no order effects. Greater gains in spatiotemporal symmetry were observed with AIH+HIT, with worse outcomes for those prescribed serotonin-mediated antidepressant medications.

CONCLUSIONS

AIH+HIT resulted in greater gains in locomotor function than normoxia+HIT. Subsequent phase III trials should further evaluate the efficacy of this intervention.

REGISTRATION

URL: https://clinicaltrials.gov/; Unique identifier: NCT04472442.

Interval training and cardiometabolic health in reproductive-aged females

Physical activity and exercise training are especially important for reproductive-aged females as exercise-induced health benefits can also affect their infants. However, levels of physical inactivity remain high among females in this age group, before, during, and after pregnancy. There is a great need for practical and feasible exercise modes to increase adherence to exercise in this population, and interval training may be a time-efficient training modality. Interval training is a form of exercise involving intermittent bouts of intense effort interspersed with recovery periods of rest or lower-intensity exercise. A substantial amount of research indicates that interval training induces superior cardiometabolic health benefits compared with iso-energetic moderate-intensity continuous exercise. This review provides a comprehensive overview of research on interval training interventions in reproductive-aged females across various life stages, focusing on the cardiometabolic health benefits. We discuss the potential role of interval training in premenopausal females with overweight/obesity, polycystic ovary syndrome, and subfertility, as well as the potential influence of oral contraceptives on cardiometabolic adaptations to interval training. Furthermore, this review also highlights recent findings supporting the beneficial role of high-intensity interval training for cardiometabolic health outcomes during pregnancy. In summary, the existing evidence suggests that interval training can improve several cardiometabolic and reproductive outcomes in females spanning different life stages. However, more research is needed to further strengthen the evidence-base for physical activity recommendations for females in their reproductive years of life.

Results of a feasibility and initial efficacy clinical trial of a high-intensity interval training program using adaptive equipment in persons with multiple sclerosis who have walking disability

BACKGROUND

High intensity interval training (HIIT) has been identified as potential stimulus for eliciting health-promoting physical activity in an efficient manner among persons with multiple sclerosis (MS). The current study aimed to examine the feasibility and initial efficacy of a 12-week HIIT program using a recumbent stepper (RSTEP) in persons with MS who have walking disability. Feasibility outcomes of interest included process (i.e., recruitment, adherence, and retention rates), resource (i.e., time and monetary costs), management (i.e., data management and safety reporting assessment), and science (i.e., safety, burden, and treatment effect assessment). We hypothesized that 12-weeks of HIIT will be feasible via meeting a priori benchmarks in process, resource, management, and scientific outcomes. The efficacy outcomes of interest included changes in aerobic fitness, physical activity, walking, upper arm function, cognition, fatigue, and depressive symptoms. We hypothesized that 12 weeks of HIIT would result in improvements in aerobic capacity, walking, upper arm function, cognition, fatigue, and depression.

METHODS

A pre-post clinical trial design was applied. Participants (N = 16) were recruited and enrolled in the 12-week RSTEP HIIT program who met the following inclusion criteria: age ≥18 years, self-reported diagnosis of MS, Patient Determined Disability Steps scale score 3.0-7.0, relapse free in past 30 days, willing to visit a University Laboratory for study protocol, asymptomatic status for maximal exercise testing, physician approval, and a self-reported ability to speak, read, and understand English. Measures of efficacy outcomes of interest included Six Minute Walk Test (6MW), Timed 25 Foot Walk Test (T25FW), the Brief International Cognitive Assessment in MS (BICAMS), 9-hole peg test (9-HPT), Expanded Disability Status Scale (EDSS), Fatigue Severity Survey (FSS), Hospital Anxiety and Depression Scale (HADS), Godin Leisure Time Exercise Questionnaire (GLTEQ), Multiple Sclerosis Walking Scale-12 (MSWS-12). Participants completed a graded maximal exercise test for measuring aerobic fitness (VO2peak) and prescription of exercise throughout the intervention. All outcomes were measured at baseline, mid-point (6-weeks), and post-intervention (12-weeks). The intervention involved 12 weeks of supervised, individualized HIIT sessions two times per week using RSTEP. The individual HIIT sessions included 10 cycles of 60 s intervals at the work rate associated with 90 % VO2peak followed by 60 s of active recovery intervals, totaling 20 minutes plus 5-minute warm-up and cool-down periods. Process, resources, management, and scientific feasibility outcomes were examined using descriptive statistics, percentage, and frequency analyses. The efficacy of the intervention was assessed using a 1-factor (Time), repeated measure analysis of variance to identify significant changes over time.

RESULTS

Fourteen of 16 participants were retained throughout the full study period and adherence with prescribed exercise sessions was 97 %. Twenty-three staff were comprehensively trained across two sites. There was only one adverse event reported that did not impact participation in the study and overall mean satisfaction rating with the program among participants was 4.7/5. There were statistically significant changes in cognitive processing speed (p = 0.002), GLTEQ (p = 0.005), and MSWS-12 (p = 0.04), but not the other outcomes of fitness, arm function, and walking. Of note, there were large effect sizes noted for peak power output (d = 1.10) and FSS (d = 1.05) despite the lack of statistically significant changes CONCLUSION: Feasibility of a 12-week individualized RSTEP HIIT program was established and participants significantly improved on measures of cognition, physical activity, and walking.

Health benefits of interval walking training

Interval walking training (IWT) is a free-living training intervention involving alternating fast and slow walking cycles. IWT is efficacious in improving physical fitness and muscle strength, and reducing factors associated with lifestyle-related diseases. In individuals with type 2 diabetes, IWT improves glycemic control directly through enhanced glucose effectiveness, challenging conventional views on mechanisms behind training-induced improvements in glycemic control. Whereas adherence to IWT in short-term studies is high, ensuring long-term adherence remains a challenge, particularly in populations with chronic diseases and/or overweight/obesity. Long-term studies in real-world settings are imperative to ascertain the widespread effectiveness of IWT and elucidate its impact on hard endpoints.

Heavy-, Severe-, and Extreme-, but Not Moderate-Intensity Exercise Increase V̇o 2max and Thresholds after 6 wk of Training

INTRODUCTION

This study assessed the effect of individualized, domain-based exercise intensity prescription on changes in maximal oxygen uptake (V̇O 2max ) and submaximal thresholds.

METHODS

Eighty-four young healthy participants (42 females, 42 males) were randomly assigned to six age, sex, and V̇O 2max -matched groups (14 participants each). Groups performed continuous cycling in the 1) moderate (MOD), 2) lower heavy (HVY1), and 3) upper heavy-intensity (HVY2) domain; interval cycling in the form of 4) high-intensity interval training (HIIT) in the severe-intensity domain, or 5) sprint-interval training (SIT) in the extreme-intensity domain; or no exercise for 6) control (CON). All training groups, except SIT, were work-matched. Training participants completed three sessions per week for 6 wk with physiological evaluations performed at PRE, MID, and POST intervention.

RESULTS

Compared with the change in V̇O 2max (∆V̇O 2max ) in CON (0.1 ± 1.2 mL·kg -1 ·min -1 ), all training groups, except MOD (1.8 ± 2.7 mL·kg -1 ·min -1 ), demonstrated a significant increase ( P < 0.05). HIIT produced the highest increase (6.2 ± 2.8 mL·kg -1 ·min -1 ) followed by HVY2 (5.4 ± 2.3 mL·kg -1 ·min -1 ), SIT (4.7 ± 2.3 mL·kg -1 ·min -1 ), and HVY1 (3.3 ± 2.4 mL·kg -1 ·min -1 ), respectively. The ΔPO at the estimated lactate threshold ( θLT ) was similar across HVY1, HVY2, HIIT, and SIT, which were all greater than CON ( P < 0.05). The ΔV̇O 2 and ΔPO at θLT for MOD was not different from CON ( P > 0.05). HIIT produced the highest ΔPO at maximal metabolic steady state, which was greater than CON, MOD, and SIT ( P < 0.05).

CONCLUSIONS

This study demonstrated that i) exercise intensity is a key component determining changes in V̇O 2max and submaximal thresholds and ii) exercise intensity domain-based prescription allows for a homogenous metabolic stimulus across individuals.

Cardiovascular and cardiorespiratory effects of high-intensity interval training in body fat responders and non-responders

This study aimed to investigate cardiovascular and cardiorespiratory adaptations to exercise intervention among participants who showed higher (responders-RSBFP) and lower (non-responders-NRSBFP) levels of body fat percentage (BFP) responsiveness. Adolescents (42.5% males) participated in a ten-week school-based high-intensity interval training (HIIT), followed by a comparison of BFP, blood pressure (BP), and cardiorespiratory fitness (CRF). RSBFP age of 16.15 ± 0.36 years, body height 170.82 ± 8.16 cm, weight 61.23 ± 12.80 kg, and BMI 20.86 ± 3.29 kg/m2. Meanwhile, NRSBFP age of 16.04 ± 0.36 years, body height 168.17 ± 8.64 cm, weight 57.94 ± 8.62 kg, and BMI 20.47 ± 2.24 kg/m2. HIIT intervention impacted BFP, with a higher decrease in the RSBFP than the NRSBFP (ΔBFPRs = - 2.30 ± 3.51(10.34%) vs. ΔBFPNRs = 1.51 ± 1.54(6.96%) p < 0.001). The primary comparison showed a statistically significant interaction effect in relation to CRF (F(1,71) = 14.12; p < 0.001). Detailed comparisons showed large and significant CRF changes in RSBFP (7.52%; d = 0.86; p < 0.001) but not in NRSBFP (2.01%; d = 0.11; p = 0.576). In addition, RSBFP and NRSBFP benefited equally in SBP (5.49%, d = 0.75; p < 0.001; 4.95%, d = 0.74; p < 0.001, respectively). These findings highlight that exercise benefits on body fat may be mainly related to gains in CRF. Due to substantial intra-individual variability in adaptation, there is a need for personalized intervention tailored for those with different reaction thresholds in body mass components.