The scientific basis for high-intensity interval training: optimising training programmes and maximising performance in highly trained endurance athletes

High-Intensity Interval Training and Sprint-Interval Training in National-Level Rowers

Purpose: The effects of two different high-intensity training methods on 2,000 m rowing ergometer performance were examined in a feasibility study of 24 national-level rowers aged 18–27 years (17 males, 2,000 m ergometer time trial 6:21.7 ± 0:14.6 (min:s) and seven females, 2,000 m ergometer 7:20.3 ± 0:12.1. Habitual training for all participants was ~12–16 h per week).

Methods: 16 high-intensity ergometer sessions were completed across two 3-week periods. Participants were allocated into two groups according to baseline 2,000 m time. High-intensity interval session-sprint-interval session (HIIT-SIT) completed eight HIIT (8 × 2.5 min intervals; 95% of 2,000 m wattage) followed by eight SIT (three sets of 7 × 30 s intervals; maximum effort). SIT-HIIT completed eight SIT sessions followed by eight HIIT sessions. Both a 2,000-m time trial and a progressive incremental test finishing with 4 min “all-out” performance were completed before and after each 3-week phase.

Results: Both groups showed similar improvements in 2,000 m time and 4 min “all-out” distance after the first 3 weeks (2,000 m time: HIIT-SIT: −2.0 ± 0.6%, mean ± 90% CL, p = 0.01; SIT-HIIT: −1.5 ± 0.3%, p = 0.01) with no significant difference between groups. HIIT-SIT demonstrated the greatest improvements in submaximal heart rate (HR) during the progressive incremental test with eight sessions of HIIT showing a greater reduction in submaximal HR than eight sessions of SIT. The net improvement of 16 high-intensity sessions on 2,000 m time was −2.5% for HIIT-SIT (−10.6 ± 3.9 s, p = 0.01) and − 2.2% for SIT-HIIT (−9.0 ± 5.7 s, p = 0.01) and for 4 min “all-out” performance was 3.1% for HIIT-SIT (36 ± 25 m, p = 0.01) and 2.8% for SIT-HIIT (33 ± 27 m, p = 0.01).

Conclusion: Eight sessions of high-intensity training can improve 2,000 m ergometer rowing performance in national-level rowers, with a further eight sessions producing minimal additional improvement. The method of high-intensity training appears less important than the dose.

Effects of High-Intensity Interval Training on Inflammatory Biomarkers in Patients with Type 2 Diabetes. A Systematic Review

Background: Due to the prevalence and incidence worldwide of type 2 diabetes, and the significant role physical activity plays in these patients, a systematic review has been conducted to find out the effects that high-intensity interval training has on inflammatory biomarkers in subjects with type 2 diabetes. This project aims to determine the effect this training modality has on inflammatory biomarkers, in addition to observing its effects on the values of body composition and determining if this is a more effective, less effective or equally effective alternative to standard aerobic or resistance training. Methods: A search was conducted in the months of November and December 2020 on different databases: Pubmed, WoS and PEDro. A protocol for this systematic review was registered in PROSPERO (Registration number: CRD42021281186). The studies selected met the previously defined inclusion criteria, and the methodological quality of the papers used was evaluated according to the Downs and Black Checklist. Results: Out of 46 studies found, seven were included. The most relevant data concerning the characteristics of the clinical trials and HIIT characteristics, the values of body composition and the biomarkers under study were extracted from each study. Moreover, the results obtained from the different studies were described. Conclusions: HIIT could have an effect on inflammatory biomarkers. There is likely to be a relationship between changes in inflammatory profile and fat loss. A controlled diet may be a good complement to reduce the inflammatory profile. Further studies are required to determine whether HIIT is a better, worse or an equivalent alternative to medium-intensity aerobic exercise to improve the inflammatory profile.

Effect of Cycle-Based High-Intensity Interval Training and Moderate to Moderate-Intensity Continuous Training in Adolescent Soccer Players

Cardiorespiratory fitness, anaerobic power, and lower extremity strength are essential for soccer players at all levels. An effective program should be developed to improve physical strength for adolescent soccer players who need to combine academic and technical training. This study analyzed the impact of short-term high intensity interval training (HIIT) training and traditional moderate intensity continuous training (MICT) on adolescent soccer players. Participants included 56 adolescent soccer players who were divided into HIIT and MICT groups. The training program was conducted 3 times a week for 4 weeks using cycle ergometer. Each session included the same resistance training program, and the characteristics of HIIT and MICT were applied to improve cardiorespiratory fitness and anaerobic power. Body composition analysis, graded exercise test for peak oxygen uptake (VO₂ peak), Wingate anaerobic power test, and isokinetic knee strength test were performed. VO₂ peak was improved in HIIT and MICT, but anaerobic threshold and heart rate recovery significantly improved in the HIIT group. Wingate anaerobic peak power had increased significantly in sets 1, 2, and 3 in the HIIT group, but showed significant improvement only in set 1 in the MICT group. The isokinetic strength improved significantly in the HIIT group at 60°/s and in the MICT group at 240°/s. There was no significant change in body composition in either group. In conclusion, short-term HIIT administered to adolescent soccer players effectively improved cardiorespiratory fitness in HIIT and MICT groups. While HIIT increased anaerobic threshold and power, MICT effectively improved muscle endurance. Short-term intensive training can be considered a time-efficient training strategy.

Acute Effects of Different Exercise Intensities on Executive Function and Oculomotor Performance in Middle-Aged and Older Adults: Moderate-Intensity Continuous Exercise vs. High-Intensity Interval Exercise

A wealth of evidence has shown that a single bout of aerobic exercise can facilitate executive function. However, none of current studies on this topic have addressed whether the magnitude of the acute-exercise benefit on executive function and oculomotor performance is influenced by different aerobic exercise modes. The present study was thus aimed toward an investigation of the acute effects of high-intensity interval exercise (HIIE) vs. moderate-intensity continuous exercise (MICE) on executive-related oculomotor performance in healthy late middle-aged and older adults. Using a within-subject design, twenty-two participants completed a single bout of 30 min of HIIE, MICE, or a non-exercise-intervention (REST) session in a counterbalanced order. The behavioral [e.g., reaction times (RTs), coefficient of variation (CV) of the RT], and oculomotor (e.g., saccade amplitude, saccade latency, and saccadic peak velocity) indices were measured when participants performed antisaccade and prosaccade tasks prior to and after an intervention mode. The results showed that a 30-min single-bout of HIIE and MICE interventions shortened the RTs in the antisaccade task, with the null effect on the CV of the RT in the late middle-aged and older adults. In terms of oculomotor metrics, although the two exercise modes could not modify the performance in terms of saccade amplitudes and saccade latencies, the participants’ saccadic peak velocities while performing the oculomotor paradigm were significantly altered only following an acute HIIE intervention. The present findings suggested that a 30-min single-bout of HIIE and MICE interventions modulated post-exercise antisaccade control on behavioral performance (e.g., RTs). Nevertheless, the HIIE relative MICE mode appears to be a more effective aerobic exercise in terms of oculomotor control (e.g., saccadic peak velocities) in late middle-aged and older adults.

Interactive Effects of Enalapril Administration and Novel HIIT Wheel-Bed Training in Aged Rats

INTRODUCTION

Growing research suggests that aerobic high-intensity interval training (HIIT) improves cardiovascular function and physical performance compared with moderate intensity continuous training (MICT). However relatively few animal models of HIIT are available to inform about the benefits of this exercise-particularly among older animals. In addition, there is little evidence for how HIIT training interacts with adjuvant pharmacological therapies known to enhance the impact of MCIT in older individuals such as Angiotensin Converting Enzyme (ACE) Inhibitors.

PURPOSE

The aim of the present study was to establish a HIIT protocol in aged rats based on forced running wheel-bed, and to subsequently (1) establish the feasibility of the HIIT protocol in a proof-of-concept study evaluating interactions between HIIT and (2) the result of combining HIIT + ACE inhibitor treatment using the ACE inhibitor enalapril.

METHODS

Two groups of rats were used in this study. The feasibility of using wheel-bed for HIIT training was tested in group one (15- and 30-month-old male rats). In the second group, 37 24-month-old Fisher 344 × Brown Norway male rats were randomly divided into four subgroups: control, enalapril, HIIT training group, and HIIT training combined with enalapril administration. The training and administration lasted for 4 weeks. After the intervention, locomotor activity, exercise tolerance, and grip strength were tested.

RESULTS

Our feasibility study suggested that middle-aged and aged rats were able to successfully complete the HIIT training. In our intervention study, HIIT training alone, regardless of adjuvant enalapril intervention, did raise treadmill exercise tolerance vs. the sedentary condition. Measures of healthspan were not negatively impacted by HIIT training.

CONCLUSION

The novel HIIT protocol based on forced running wheel-bed was successfully employed in aged rats. We conclude that future studies should compare the results and of multi-modal intervention strategies which include both HIIT and MICT in combination with adjuvant therapies such as enalapril to improve exercise tolerance and other global indices of healthspan.

The Effects of Running Compared with Functional High-Intensity Interval Training on Body Composition and Aerobic Fitness in Female University Students

High-intensity interval running (HIIT-R) and high-intensity functional training (HIFT) are two forms of HIIT exercise that are commonly used. The purpose of this study was to determine the effects of HIFT on aerobic capacity and body composition when compared to HIIT-R in females. Twenty healthy, untrained female university students (age 20.5 ± 0.7 year) were randomly assigned to a 12-week HIIT-R or HIFT intervention. The HIIT-R group involved a 30 s maximal shuttle run with a 30 s recovery period, whereas the HIFT involved multiple functional exercises with a 2:1 work-active recovery ratio. Body composition, VO₂max, and muscle performance were measured before and post intervention. As a result, HIIT-R and HIIT-F stimulated similar improvements in VO₂max (17.1% ± 5.6% and 12.7% ± 6.7%, respectively, p > 0.05). Only the HIIT-F group revealed significant improvements in muscle performance (sit-ups, 16.5% ± 3.1%, standing broad jump 5.1% ± 2.2%, p < 0.05). Body fat percentage decreased (17.1% ± 7.4% and 12.6% ± 5.1%, respectively, p < 0.05) in both HIIT-R and HIIT-F with no between-group differences. We concluded that HIFT was equally effective in promoting body composition and aerobic fitness compared to HIIT-R. HIFT resulted in improved muscle performance, whereas the HIIT-R protocol demonstrated no gains.

The Prediction of Running Velocity during the 30-15 Intermittent Fitness Test Using Accelerometry-Derived Metrics and Physiological Parameters: A Machine Learning Approach

Measuring exercise variables is one of the most important points to consider to maximize physiological adaptations. High-intensity interval training (HIIT) is a useful method to improve both cardiovascular and neuromuscular performance. The 30–15_IFT is a field test reflecting the effort elicited by HIIT, and the final velocity reached in the test is used to set the intensity of HIIT during the training session. In order to have a valid measure of the velocity during training, devices such as GPS can be used. However, in several situations (e.g., indoor setting), such devices do not provide reliable measures. The aim of the study was to predict exact running velocity during the 30–15_IFT using accelerometry-derived metrics (i.e., Player Load and Average Net Force) and heart rate (HR) through a machine learning (ML) approach (i.e., Support Vector Machine) with a leave-one-subject-out cross-validation. The SVM approach showed the highest performance to predict running velocity (r = 0.91) when compared to univariate approaches using PL (r = 0.62), AvNetForce (r = 0.73) and HR only (r = 0.87). In conclusion, the presented multivariate ML approach is able to predict running velocity better than univariate ones, and the model is generalizable across subjects.

Effects of Increased Load of Low- Versus High-Intensity Endurance Training on Performance and Physiological Adaptations in Endurance Athletes

PURPOSE

To compare the effects of increased load of low- versus high-intensity endurance training on performance and physiological adaptations in well-trained endurance athletes.

METHODS

Following an 8-week preintervention period, 51 (36 men and 15 women) junior cross-country skiers and biathletes were randomly allocated into a low-intensity (LIG, n = 26) or high-intensity training group (HIG, n = 25) for an 8-week intervention period, load balanced using the overall training impulse score. Both groups performed an uphill running time trial and were assessed for laboratory performance and physiological profiling in treadmill running and roller-ski skating preintervention and postintervention.

RESULTS

Preintervention to postintervention changes in running time trial did not differ between groups (P = .44), with significant improvements in HIG (-2.3% [3.2%], P = .01) but not in LIG (-1.5% [2.9%], P = .20). There were no differences between groups in peak speed changes when incremental running and roller-ski skating to exhaustion (P = .30 and P = .20, respectively), with both modes being significantly improved in HIG (2.2% [3.1%] and 2.5% [3.4%], both P < .01) and in roller-ski skating for LIG (1.5% [2.4%], P < .01). There was a between-group difference in running maximal oxygen uptake changes (P = .04), tending to improve in HIG (3.0% [6.4%], P = .09) but not in LIG (-0.7% [4.6%], P = .25). Changes in roller-ski skating peak oxygen uptake differed between groups (P = .02), with significant improvements in HIG (3.6% [5.4%], P = .01) but not in LIG (-0.1% [0.17%], P = .62).

CONCLUSION

There was no significant difference in performance adaptations between increased load of low- versus high-intensity training in well-trained endurance athletes, although both methods improved performance. However, increased load of high-intensity training elicited better maximal oxygen uptake adaptations compared to increased load of low-intensity training.

Acute affective responses to high-intensity interval exercise: Implications on the use of different stimulus-recovery amplitudes

The effect of high-intensity interval exercise (HIIE) on affective responses is unclear due to the several variables of HIIE, which may be minimized by using derived variables (e.g. amplitude). The amplitude reflects the difference between stimulus and recovery intensities, being more representative of the physiological changes than central tendency variables such as average intensity. This study aimed to compare the affective responses in HIIE sessions in different amplitudes with a vigorous-intensity continuous exercise (VICE) session. Eleven participants completed five sessions. The peak oxygen consumption (VO_2Peak) and peak power (W_peak) were measured. Participants performed one VICE and three HIIE sessions (10x[1min-90%W_Peak/1min-50%W_Peak]; 10x[1min-100%W_Peak/1min-40%W_Peak]; and 10x[1min-110%W_Peak/1min-40%W_Peak]). The exercise sessions were performed at the same average intensity (70%W_Peak) and duration (20 min). The Feeling Scale (FS) was applied in each minute throughout the exercise sessions. Regarding the FS responses, a two-way repeated-measures ANOVA showed no significant interaction for FS (P=0.093) or main effect for condition (P=0.206) and time (P=0.078), indicating that irrespective of the amplitude of the HIIE, FS results were similar between conditions. The effect size (ES) analysis showed a small effect in favour of HIIE-90/50 (ES=0.30) and HIIE-100/40 (ES=0.26) and a null effect on HIIE-110/30 (ES=0.08) when compared to VICE. Chi-squared analysis showed no significant differences between conditions in the number of participants that reduced, maintained, or increased the FS from pre-exercise to last stimulus and recovery indicating a high variability of the affective responses. HIIE sessions provide similar affective responses when performed at the same average intensity, even with different amplitudes.

Neuromuscular Adjustments Following Sprint Training with Ischemic Preconditioning in Endurance Athletes: Preliminary Data

This preliminary study examined the effect of chronic ischemic preconditioning (IPC) on neuromuscular responses to high-intensity exercise. In a parallel-group design, twelve endurance-trained males (VO2max 60.0 ± 9.1 mL·kg-1·min-1) performed a 30-s Wingate test before, during, and after 4 weeks of sprint-interval training. Training consisted of bi-weekly sessions of 4 to 7 supra-maximal all-out 30-s cycling bouts with 4.5 min of recovery, preceded by either IPC (3 × 5-min of compression at 220 mmHg/5-min reperfusion, IPC, n = 6) or placebo compressions (20 mmHg, PLA, n = 6). Mechanical indices and the root mean square and mean power frequency of the electromyographic signal from three lower-limb muscles were continuously measured during the Wingate tests. Data were averaged over six 5-s intervals and analyzed with Cohen's effect sizes. Changes in peak power output were not different between groups. However, from mid- to post-training, IPC improved power output more than PLA in the 20 to 25-s interval (7.6 ± 10.0%, ES 0.51) and the 25 to 30-s interval (8.8 ± 11.2%, ES 0.58), as well as the fatigue index (10.0 ± 2.3%, ES 0.46). Concomitantly to this performance difference, IPC attenuated the decline in frequency spectrum throughout the Wingate (mean difference: 14.8%, ES range: 0.88-1.80). There was no difference in root mean square amplitude between groups. These preliminary results suggest that using IPC before sprint training may enhance performance during a 30-s Wingate test, and such gains occurred in the last 2 weeks of the intervention. This improvement may be due, in part, to neuromuscular adjustments induced by the chronic use of IPC.

Novel use of radio frequency identification (RFID) provides a valid measure of indoor stair-based physical activity

This study sought to test the validity of radio frequency identification (RFID) technology to measure indoor stair walking. RFID and Bluetooth sensors (accelerometers with the proximity function) were placed at landings across three floors within a stairwell. Participants (n = 29) were randomized to stair walking or sedentary control and concomitantly wore RFID tags at the hip, chest and neck. An accelerometer worn at the hip captured criterion physical activity data. RFID devices detected sedentary control and stair walking participants (mean RFID detections: 15.50, 47.33 respectively). Neck lanyard RFID tags were detected most frequently. RFID correctly classified all participants in both groups. RFID-based energy expenditure estimates were strongly correlated with accelerometer estimates (r = 0.78-0.94). Percent agreement for floor detection between the Bluetooth and RFID readers (38.6%) was consistent with known limitations of Bluetooth proximity sensing. It is concluded that, during self-paced stair walking in young adults, RFID devices provide valid data on participant movement and estimated energy expenditure.

Physiological and performance responses of sprint interval training and endurance training in Gaelic football players

PURPOSE

While ideal for developing aerobic capacity, traditional endurance training (ET) is extremely time-consuming and may lack the specificity to maintain indices of speed and power in team sport athletes. In contrast, low-volume short-duration sprint interval training (SIT) has been shown to improve [Formula: see text]O2max to a similar extent as ET. However, to date, few studies have compared the effects of running-based SIT and ET, on aerobic capacity and indices of speed and power of trained team sport athletes.

METHODS

Club level male Gaelic football players were randomly assigned to SIT (n = 13; 26.5 ± 4.87 years) or ET (n = 12; 25.4 ± 2.58 years) groups. Participants trained 3 days week-1 for 6 weeks. [Formula: see text]O2max, RE, v[Formula: see text]O2max, blood lactate concentrations, Wingate test performance, running speed, jump performance and intermittent endurance performance (IEP) were measured at baseline and after 6 weeks.

RESULTS

An increase in [Formula: see text]O2max (p < 0.05), v[Formula: see text]O2max (p < 0.001) and IEP (p < 0.001) following 6 weeks of both SIT and ET was observed. Wingate mean power (p < 0.001), peak power (p < 0.001) and fatigue index (p < 0.005) were all significantly improved following training in both groups. Velocity at LT was significantly higher and performance in the 20-m running speed and VJ tests were significantly reduced post training in the ET group (all p < 0.005).

CONCLUSION

Despite the large difference in total training time, a running-based protocol of SIT is a time efficient training method for improving aerobic capacity and IEP while maintaining indices of lower body power and running speed in team-sport players.

Bibliometric Review to Explore Emerging High-Intensity Interval Training in Health Promotion: A New Century Picture

Background: High-intensity interval training (HIIT) is an emerging exercise strategy and is considered to be a recipe for health promotion. This study aimed to systematically identify collaboration networks, track research trends, highlight current hotspots, and predict future frontiers in HIIT and its applications in health promotion since the start of the new century.

Methods: Relevant original publications were obtained from the Science Citation Index Expanded of the Web of Science Core Collection (WoSCC) database between 2001 and 2020. CiteSpace and VOSviewer software were used to perform bibliometric visualization and comparative analysis of involved indexes that included countries, institutions, journals, authors, references, and keywords.

Results: A total of 572 papers were included, and the trend of annual publications showed a remarkable growth. The United States and the University of Exeter were the most productive country and institutions, respectively, with 107 and 18 publications, respectively. European Journal of Applied Physiology took the lead in the number of published articles, and Medicine and Science in Sports and Exercise ranked first in the cocitation counts. Barker AR and Gibala MJ were considered as the most productive and the most highly-cited authors.

Conclusions: “Health risks,” “adolescent,” and “aging” are the three noteworthy topics during the evolution of HIIT-health promotion (HIIT-HP) research. The current research hotspots of HIIT and its practices in the health promotion domain lies in “metabolic diseases,” “cardiovascular diseases,” “neurological diseases,” and “musculoskeletal diseases.” The authors summarize that “prevention and rehabilitation,” “micro and molecular level,” and “cognition and mental health” are becoming frontiers and focus on the health topics related to HIIT in the upcoming years, which are worthy of further exploration.

The effect of high-intensity interval training on exercise capacity in post-myocardial infarction patients: a systematic review and meta-analysis

AIMS

Exercise-based cardiac rehabilitation has been recommended a treatment for patients with cardiovascular disease. Nevertheless, it remains controversial which exercise characteristics are most beneficial for post-myocardial infarction (MI) patients. We performed a systematic review and meta-analysis to investigate the effects of high-intensity interval training (HIIT) in these patients.

METHODS AND RESULTS

We searched PubMed, Embase, the Cochrane Library, China National Knowledge Infrastructure (CNKI), Chinese Science and Technology Periodical Database (VIP), and Wanfang Dataset (from the earliest date available to February 2021) for randomized controlled trials and cohort studies that evaluated the effects of HIIT on post-MI patients. Studies were selected according to inclusion and exclusion criteria. Data synthesis was performed with R software version 4.0.1. Eight studies met the study criteria, including 387 patients. Compared to the control group [moderate-intensity continuous training (MICT) and/or routine physical activity], HIIT significantly improved peak oxygen uptake (peak VO2) [mean difference = 3.83 mL/kg/min, 95% confidence interval (CI) (3.25, 4.41), P < 0.01]. No significant difference in systolic and diastolic blood pressures, peak and resting heart rate, left ventricular ejection fraction, left ventricular end-diastolic volume, and the quality of life was found between HIIT group and control group. The duration of follow-up ranged from 6 to 12 weeks. The incidence of adverse events was similar between groups [risk difference = 0.01, 95% CI (-0.02, 0.04), P = 0.53].

CONCLUSION

Compared with MICT and routine physical activity, HIIT could significantly improve exercise capacity in post-MI patients, and appears to be safe.

Acute effects of high-intensity interval training and moderate-intensity continuous exercise on BDNF and irisin levels and neurocognitive performance in late middle-aged and older adults

The purposes of the present study were (1) to explore and compare the acute effects of high-intensity interval training (HIIT) and moderate-intensity continuous exercise (MICE) on neurocognitive performance and molecular biomarkers in late middle-aged and older adults, and (2) to examine the relationships of HIIT/MICE exercise-induced neurocognitive changes with changes in circulating irisin and BDNF levels elicited by different acute exercise modes. Using a within-subject design, twenty-one participants completed an acute bout of 30 min of HIIT, MICE, or a non-exercise-intervention (REST) session in a counterbalanced order. The neuropsychological [i.e., accuracy rate (AR) and reaction time (RT)] and neurophysiological [i.e., event-related potential (ERP) P3 latency and amplitude] indices were simultaneously measured when the participants performed a working memory task at baseline and after an intervention mode. Blood samples were also taken before and after the intervention mode. The results showed that, although ARs were significantly increased only via the MICE intervention mode, the acute HIIT and MICE interventions improved RT performance and increased ERP P3 amplitudes in the late middle-aged and older adults under consideration. Serum BDNF levels were significantly increased with the acute HIIT and MICE interventions, and significant irisin level increases were only observed following the HIIT intervention. However, changes in the levels of Irisin and BDNF pre- and post-intervention were not correlated with changes in neurocognitive performance, with the exception of the correlation between the changes in irisin levels and RTs with acute exercise in the MICE intervention mode. The present findings suggested similar beneficial effects on neurocognitive performance (i.e., RTs and ERP P3 amplitudes) and peripheral BDNF levels following MICE and HIIT interventions in the middle-aged and older adults. In terms of ARs and irisin, the two acute exercise modes appear to induce divergent effects. Irisin may play a potential facilitating role in the neuropsychological (e.g., RT) performance of working memory in such a group. However, the mechanisms remain to be determined.

Menthol Mouth Rinsing Is More Than Just a Mouth Wash-Swilling of Menthol to Improve Physiological Performance

Interventions that solely act on the central nervous system (CNS) are gaining considerable interest, particularly products consumed through the oral cavity. The oropharyngeal cavity contains a wide array of receptors that respond to sweet, bitter, and cold tastants, all of which have been shown to improve physiological performance. Of late, the ergogenic benefits of carbohydrate (CHO) and caffeine (CAF) mouth rinsings (MRs) have been widely studied; however, less is known about menthol (MEN). That the physiological state and environmental conditions impact the response each product has is increasingly recognized. While the effects of CHO and CAF MRs have been thoroughly studied in both hot and thermoneutral conditions, less is known about MEN as it has only been studied in hot environments. As such, this review summarizes the current knowledge regarding the MEN MR and exercise modality, frequency of the mouth rinse, and mouth rinse duration and compares two different types of study designs: time trials vs. time to exhaustion (TTE).

Protein Composition of Circulating Extracellular Vesicles Immediately Changed by Particular Short Time of High-Intensity Interval Training Exercise

Introduction/Purpose

High-intensity interval training (HIIT) promotes various biological processes and metabolic effects in multiple organs, but the role of extracellular vesicles (EVs) released from a variety of cells is not fully understood during HIIT exercise (HIIT-Ex). We investigated the changes in circulating number and proteomic profile of EVs to assess the effect of HIIT-Ex.

Methods

Seventeen young men (median age, 20 years) were enrolled in the study. Total duration of the HIIT-Ex was 4 min. Blood samples were collected from before HIIT-Ex (pre-HIIT-Ex), at the immediate conclusion of HIIT-Ex (T₀), at 30 min (T₃₀), and at 120 min after HIIT-Ex. The pulse rate and systolic blood pressure were measured. Circulating EVs were characterized, and EV proteins were detected via nano liquid chromatography tandem mass spectrometry.

Results

The pulse rate and systolic blood pressure at T₀ to pre-HIIT-Ex were significantly higher. Circulating EV number was significantly altered throughout the HIIT-Ex, and the source of circulating EVs included skeletal muscle, hepatocytes, and adipose tissue. Proteomic analysis identified a total of 558 proteins within isolated circulating EVs from pre-HIIT-Ex, T₀, and T₃₀. Twenty proteins in total were significantly changed at pre-HIIT-Ex, T₀, and T₃₀ and are involved in a variety of pathways, such as activation of coagulation cascades, cellular oxidant detoxification, and correction of acid–base imbalance. Catalase and peroxiredoxin II were increased at T₀.

Conclusion

The circulating EV composition can be immediately changed by particularly a short time of HIIT-Ex, indicating that EVs may intercommunicate across various organs rapidly in response to HIIT-Ex.

Similar Anaerobic and Aerobic Adaptations After 2 High-Intensity Interval Training Configurations: 10:5 s vs. 20:10 s Work-to-Rest Ratio

ABSTRACT

Moghaddam, M, Estrada, CA, Muddle, TWD, Magrini, MA, Jenkins, NDM, and Jacobson, BH. Similar anaerobic and aerobic adaptations after 2 high-intensity interval training configurations: 10:5 s vs. 20:10 s work-to-rest ratio. J Strength Cond Res 35(6): 1685-1692, 2021-This study compares the effects of 2 high-intensity interval training (HIIT) configurations, a 10-5 vs. a 20-10 second work-to-rest ratio, on anaerobic and aerobic performance. Thirty-four individuals were randomly assigned to 10-5-HIIT (n = 17) and 20-10-HIIT (n = 17) groups to complete 6 cycles of 6 exercises, 3 days a week for 4 weeks. The 10-5-HIIT was performed with 10 s:5 s work-to-rest ratio with 1-minute recovery between cycles, while the 20-10-HIIT was performed with 20 s:10 s work-to-rest ratio followed by a 2-minute recovery. Anaerobic (i.e., peak power [PP], anaerobic capacity [AC], anaerobic power [AP], and total work [TW]) and aerobic fitness (i.e., time to exhaustion [TE], absolute V̇o2max [A-V̇o2max], relative V̇o2max [R-V̇o2max]) were measured with pre-training and post-training intervention. A significant main effect time was observed for both 10-5-HIIT and 20-10-HIIT (p < 0.05) in PP (9.2%, 5.7%); AC (14.9%, 8.6%); AP (9.0%, 6.2%); TW (15.1%, 8.5%); TE (4.3%, 5.5%); A-V̇o2max (9.4%, 8.9%); R-V̇o2max (8.5%, 8.2%), respectively. In conclusion, individuals may be able to achieve similar health benefits as 20-10-HIIT by performing 10-5-HIIT, despite exercising for 50% less total time. High-intensity interval training has been suggested as a "time-efficient" mode of exercise that can mitigate the most significant barrier to physical activity, "lack of time." Both 10-5-HIIT and 20-10-HIIT can induce performance adaptations to a similar extent. However, because of shorter time commitment, performing 10-5-HIIT at 10 s:5 s work-to-rest ratio may offer a shorter and equally efficient interval. Functional fitness training during HIIT protocols seems to be as beneficial as ergometer-based HIIT to improve anaerobic and aerobic performance.

The Association Between the Acute:Chronic Workload Ratio and Running-Related Injuries in Dutch Runners: A Prospective Cohort Study

OBJECTIVE

To investigate the association between the acute:chronic workload ratio (ACWR) and running-related injuries (RRI).

METHODS

This is a secondary analysis using a database composed of data from three studies conducted with the same RRI surveillance system. Longitudinal data comprising running exposure (workload) and RRI were collected biweekly during the respective cohorts' follow-up (18-65 weeks). ACWR was calculated as the most recent (i.e., acute) external workload (last 2 weeks) divided by the average external (i.e., chronic) workload of the last 4, 6, 8, 10 and 12 weeks. Three methods were used to calculate the ACWR: uncoupled, coupled and exponentially weighted moving averages (EWMA). Bayesian logistic mixed models were used to analyse the data.

RESULTS

The sample was composed of 435 runners. Runners whose ACWR was under 0.70 had about 10% predicted probability of sustaining RRI (9.6%; 95% credible interval [CrI] 7.5-12.4), while those whose ACWR was higher than 1.38 had about 1% predicted probability of sustaining RRI (1.3%; 95% CrI 0.7-1.7). The association between the ACWR and RRI was significant, varying from a small to a moderate association (1-10%). The higher the ACWR, the lower the RRI risk.

CONCLUSIONS

The ACWR showed an inversely proportional association with RRI risk that can be represented by a smooth L-shaped, second-order, polynomial decay curve. The ACWR using hours or kilometres yielded similar results. The coupled and uncoupled methods revealed similar associations with RRIs. The uncoupled method presented the best discrimination for ACWR strata. The EWMA method yielded sparse and non-significant results.

Effect of four different forms of high intensity training on BDNF response to Wingate and Graded Exercise Test

This study examined the effects of a nine-week intervention of four different high-intensity training modalities [high-intensity functional training (HIFT), high-intensity interval training (HIIT), high-intensity power training (HIPT), and high-intensity endurance training (HIET)] on the resting concentration of brain-derived neurotropic factor (BDNF). In addition, we evaluated the BDNF responses to Graded Exercise Test (GXT) and Wingate Anaerobic Test (WAnT) in men. Thirty-five healthy individuals with body mass index 25.55 ± 2.35 kg/m2 voluntarily participated in this study and were randomly assigned into four training groups. During nine-weeks they completed three exercise sessions per week for one-hour. BDNF was analyzed before and after a GXT and WAnT in two stages: (stage 0-before training and stage 9-after nine weeks of training). At stage 0, an increase in BDNF concentration was observed in HIFT (33%; p < 0.05), HIPT (36%; p < 0.05) and HIIT (38%; p < 0.05) after GXT. Even though HIET showed an increase in BDNF (10%) this was not statistically significant (p > 0.05). At stage 9, higher BDNF levels after GXT were seen only for the HIFT (30%; p < 0.05) and HIIT (18%; p < 0.05) groups. Reduction in BDNF levels were noted after the WAnT in stage 0 for HIFT (- 47%; p < 0.01), HIPT (- 49%; p < 0.001), HIET (- 18%; p < 0.05)], with no changes in the HIIT group (- 2%). At stage 9, BDNF was also reduced after WAnT, although these changes were lower compared to stage 0. The reduced level of BDNF was noted in the HIFT (- 28%; p < 0.05), and HIPT (- 19%;p < 0.05) groups. Additionally, all groups saw an improvement in VO2max (8%; p < 0.001), while BDNF was also correlated with lactate and minute ventilation and selected WAnT parameters. Our research has shown that resting values of BDNF after nine weeks of different forms of high-intensity training (HIT) have not changed or were reduced. Resting BDNF measured at 3th (before GXT at stage 9) and 6th day after long lasting HITs (before WAnT at stage 9) did not differed (before GXT), but in comparison to the resting value before WAnT at the baseline state, was lower in three groups. It appears that BDNF levels after one bout of exercise is depended on duration time, intensity and type of test/exercise.

Acute Effects of Work Rest Interval Duration of 3 HIIT Protocols on Cycling Power in Trained Young Adults

High-Intensity Interval Training (HIIT) is described as a succession of short duration and maximum or near-maximum intensity efforts, alternated by recovery periods during which exercise continues at a lower intensity (active recovery) or is interrupted (passive recovery). Our objective was to evaluate the acute responses of three HIIT protocols of different work/rest interval times over the total time of the session, with self-selectable load and up to exhaustion, “all out”.The sample was composed of 22 male participants (n = 22) between 19 and 24 years old. The HIIT protocol consisted of one of the three HIIT protocols, of 30, 60 and 90 s density ratio 1:1 and with passive rest, with a total exercise duration of 10 min. The test was performed in a cycloergometer set in workload mode independent of the pedaling frequency. The comparison of the three HIIT protocols shows that the duration of the work/rest intervals, starting from 30 s of work, in the cycloergometer, there are no significant differences in the levels of lactate concentration in the blood, nor in the heart rate, since a similar amount is obtained in the three protocols. The percentage of maximum power developed reached in each HIIT protocol is related to the duration of the working intervals.

The Effects of 15 or 30 s SIT in Normobaric Hypoxia on Aerobic, Anaerobic Performance and Critical Power

Sprint interval training (SIT) is a concept that has been shown to enhance aerobic-anaerobic training adaptations and induce larger effects in hypoxia. The purpose of this study was to examine the effects of 4 weeks of SIT with 15 or 30 s in hypoxia on aerobic, anaerobic performance and critical power (CP). A total of 32 male team players were divided into four groups: SIT with 15 s at FiO₂: 0.209 (15 N); FiO₂: 0.135 (15 H); SIT with 30 s at FiO₂: 0.209 (30 N); and FiO₂: 0.135 (30 H). VO_2max did not significantly increase, however time-to-exhaustion (TTE) was found to be significantly longer in the post test compared to pre test (p = 0.001) with no difference between groups (p = 0.86). Mean power (MPw.kg) after repeated wingate tests was significantly higher compared to pre training in all groups (p = 0.001) with no difference between groups (p = 0.66). Similarly, CP was increased in all groups with 4 weeks of SIT (p = 0.001) with no difference between groups (p = 0.82). This study showed that 4 weeks of SIT with 15 and 30 s sprint bouts in normoxia or hypoxia did not increased VO_2max in trained athletes. However, anerobic performance and CP can be increased with 4 weeks of SIT both in normoxia or hypoxia with 15 or 30 s of sprint durations.

Aerobic capacity and respiratory patterns are better in recreational basketball-engaged university students than age-matched untrained males

Study aim: To asses and compare the aerobic capacity and respiratory parameters in recreational basketball-engaged university students with age-matched untrained young adults.

Material and methods: A total of 30 subjects were selected to took part in the study based on recreational-basketball activity level and were assigned to a basketball (BG: n = 15, age 22.86 ± 1.35 yrs., body height 185.07 ± 5.95 cm, body weight 81.21 ± 6.15 kg) and untrained group (UG: n = 15, age 22.60 ± 1.50 yrs., body height 181.53 ± 6.11 cm, body weight 76.89 ± 7.30 kg). Inspiratory vital capacity (IVC), forced expiration volume (FEV1), FEV1/IVC ratio, maximal oxygen consumption (VO2max), ventilatory threshold (VO2VT) and time to exhaustion, were measured in all subjects. Student T-test for independent Sample and Cohen’s d as the measure of the effect size were calculated.

Results: Recreational basketball-engaged students (EG) reached significantly greater IVC (t = 7.240, p < 0.001, d = 1.854), FEV1 (t = 10.852, p < 0.001, d = 2.834), FEV1/IVC ratio (t = 6.370, p < 0.001, d = 3.920), maximal oxygen consumption (t = 9.039, p < 0.001, d = 3.310), ventilatory threshold (t = 9.859, p < 0.001, d = 3.607) and time to exhaustion (t = 12.361, p < 0.001, d = 4.515) compared to UG.

Conclusions: Long-term exposure to recreational basketball leads to adaptive changes in aerobic and respiratory parameters in male university students.

Superior Physiological Adaptations After a Microcycle of Short Intervals Versus Long Intervals in Cyclists

PURPOSE

To compare the effects of a 1-week high-intensity aerobic-training shock microcycle composed of either 5 short-interval sessions (SI; n = 9, 5 series with 12 × 30-s work intervals interspersed with 15-s recovery and 3-min recovery between series) or 5 long-interval sessions (LI; n = 8, 6 series of 5-min work intervals with 2.5-min recovery between series) on indicators of endurance performance in well-trained cyclists.

METHODS

Before and following 6 days with standardized training loads after the 1-week high-intensity aerobic-training shock microcycle, both groups were tested in physiological determinants of endurance performance.

RESULTS

From pretraining to posttraining, SI achieved a larger improvement than LI in maximal oxygen uptake (5.7%; 95% confidence interval, 1.3-10.3; P = .015) and power output at a blood lactate concentration of 4 mmol·L-1 (3.8%; 95% confidence interval, 0.2-7.4; P = .038). There were no group differences in changes of fractional use of maximal oxygen uptake at a workload corresponding to a blood lactate concentration of 4 mmol·L-1, gross efficiency, or the 1-minute peak power output from the maximal-oxygen-uptake test.

CONCLUSION

The SI protocol may induce superior changes in indicators of endurance performance compared with the LI protocol, indicating that SI can be a good strategy during a 1-week high-intensity aerobic-training shock microcycle in well-trained cyclists.

Is High-Intensity Interval Training Suitable to Promote Neuroplasticity and Cognitive Functions after Stroke?

Stroke-induced cognitive impairments affect the long-term quality of life. High-intensity interval training (HIIT) is now considered a promising strategy to enhance cognitive functions. This review is designed to examine the role of HIIT in promoting neuroplasticity processes and/or cognitive functions after stroke. The various methodological limitations related to the clinical relevance of studies on the exercise recommendations in individuals with stroke are first discussed. Then, the relevance of HIIT in improving neurotrophic factors expression, neurogenesis and synaptic plasticity is debated in both stroke and healthy individuals (humans and rodents). Moreover, HIIT may have a preventive role on stroke severity, as found in rodents. The potential role of HIIT in stroke rehabilitation is reinforced by findings showing its powerful neurogenic effect that might potentiate cognitive benefits induced by cognitive tasks. In addition, the clinical role of neuroplasticity observed in each hemisphere needs to be clarified by coupling more frequently to cellular/molecular measurements and behavioral testing.

Effect of Resistance Training of Psoas Major in Combination With Regular Running Training on Performance in Long-Distance Runners

PURPOSE

The study determined whether the increase in the cross-sectional area (CSA) of psoas major, which is known as a hip-flexion muscle, by resistance training combined with running training improves the performance of long-distance runners.

METHODS

Subjects were 8 well-trained male long-distance runners. The personal best time in a 5000-m race was 15:10.0 (0:20.5) (mean [SD]). Each subject performed resistance training twice per week with running training for 12 weeks. The authors used 3 resistance training regimens that would train the hip flexor muscles. Training intensity was a maximum of 10 repetitions. The training amount was 3 sets × 10 times during the first 4 weeks followed by 4 sets × 10 times during the last 8 weeks. The authors measured the CSA of psoas major using magnetic resonance imaging and the performance of long-distance runners using a constant velocity running test before (pre) and after (post) the training term.

RESULTS

The combination training significantly (P < .01, d = 0.34) increased the CSA of psoas major (pre: 16.2 [1.5] cm2, post: 16.7 [1.4] cm2) and significantly (P < .01, d = 1.41) improved the duration of the constant velocity running test (pre: 500 [108] s, post: 715 [186] s). Moreover, multiple regression analysis showed that the pre to post change in the duration of the constant velocity exercise was significantly correlated with the change in CSA of the psoas major.

CONCLUSION

The authors suggest that resistance training of psoas major with running training is correlated with an improvement in the performance of long-distance runners.

Impact of COVID-19 Lockdown on Serie A Soccer Players' Physical Qualities

In March 2020, the COVID-19 pandemic forced most activities in Italy, including soccer, to cease. During lockdown, players could only train at home, with limited evidence regarding the effect of this period. Therefore, this study aimed to investigate the effect of COVID-19 lockdown on professional soccer players' physical performance. Aerobic fitness and vertical jump were assessed before and after four periods in two different seasons: COVID-19 lockdown, competitive period before lockdown, competitive period and summer break of the 2016-2017 season. Linear mixed models were used to examine within-period changes and between-period differences in changes observed during COVID-19 lockdown and the three other periods. Within-period changes in aerobic fitness showed a significant improvement following COVID-19 lockdown (p<0.001) and a significant decline during summer break (p<0.001). Between-period differences were significant in the comparison of COVID-19 lockdown with both the competitive 2019-2020 season (p<0.01) and summer break (p<0.001). For the vertical jump, only the between-period comparison revealed significant differences as the changes associated with COVID-19 lockdown were worse than those of the two competitive periods, for both absolute (p<0.05; p<0.001) and relative peak power (p<0.01; p<0.001). Home-based training during lockdown was effective to improve aerobic fitness, although it did not allow players to maintain their competitive period's power levels.

The dose-response relationship between interval-training and VO2max in well-trained endurance runners: A systematic review

Success in endurance running is primarily determined by maximal aerobic power (VO_2max), fractional utilization, and running economy (RE). Within the literature, two training modalities have been identified to improve VO_2max; continuous training (CT) and interval-training (IT). The efficacy of IT to improve VO_2max in well-trained runners remains equivocal, as does whether a dose-response relationship exists between the IT training load performed and changes in VO_2max. A keyword search was performed in five electronic databases. Seven studies met the inclusion criteria for this systematic review. The training impulse (TRIMP) was calculated to analyse relationships between training load and changes in VO_2max, by calculating the time accumulated in certain intensity domains throughout a training intervention. Non-significant (P>0.05) improvements in VO_2max were reported in six studies, with only one study reporting a significant (P<0.05) improvement following the IT interventions. A relationship between the training session impulse of the interval-training performed (IT S_TRIMP) and VO_2max improvements were observed. The efficacy of IT to improve VO_2max in well-trained runners remains equivocal, nevertheless, the novel method of training-load analysis demonstrates a relationship between the IT S_TRIMP and VO_2max improvements. This provides practical application for the periodization of IT within the training regime of well-trained distance runners.

Blood-flow-restricted exercise: Strategies for enhancing muscle adaptation and performance in the endurance-trained athlete

NEW FINDINGS

What is the topic of this review? Blood-flow-restricted (BFR) exercise represents a potential approach to augment the adaptive response to training and improve performance in endurance-trained individuals. What advances does it highlight? When combined with low-load resistance exercise, low- and moderate-intensity endurance exercise and sprint interval exercise, BFR can provide an augmented acute stimulus for angiogenesis and mitochondrial biogenesis. These augmented acute responses can translate into enhanced capillary supply and mitochondrial function, and subsequent endurance-type performance, although this might depend on the nature of the exercise stimulus. There is a requirement to clarify whether BFR training interventions can be used by high-performance endurance athletes within their structured training programme.

ABSTRACT

A key objective of the training programme for an endurance athlete is to optimize the underlying physiological determinants of performance. Training-induced adaptations are governed by physiological and metabolic stressors, which initiate transcriptional and translational signalling cascades to increase the abundance and/or function of proteins to improve physiological function. One important consideration is that training adaptations are reduced as training status increases, which is reflected at the molecular level as a blunting of the acute signalling response to exercise. This review examines blood-flow-restricted (BFR) exercise as a strategy for augmenting exercise-induced stressors and subsequent molecular signalling responses to enhance the physiological characteristics of the endurance athlete. Focus is placed on the processes of capillary growth and mitochondrial biogenesis. Recent evidence supports that BFR exercise presents an intensified training stimulus beyond that of performing the same exercise alone. We suggest that this has the potential to induce enhanced physiological adaptations, including increases in capillary supply and mitochondrial function, which can contribute to an improvement in performance of endurance exercise. There is, however, a lack of consensus regarding the potency of BFR training, which is invariably attributable to the different modes, intensities and durations of exercise and BFR methods. Further studies are needed to confirm its potential in the endurance-trained athlete.

A Comparison of the Gluco-Regulatory Responses to High-Intensity Interval Exercise and Resistance Exercise

High-intensity interval exercise and resistance exercise both effectively lower blood glucose; however, it is not clear whether different regulatory mechanisms exist. This randomised cross-over study compared the acute gluco-regulatory and the physiological responses of high-intensity interval exercise and resistance exercise. Sixteen (eight males and eight females) recreationally active individuals, aged (mean ± SD) 22 ± 7 years, participated with a seven-day period between interventions. The high-intensity interval exercise trial consisted of twelve, 30 s cycling intervals at 80% of peak power capacity and 90 s active recovery. The resistance exercise trial consisted of four sets of 10 repetitions for three lower-limb exercises at 80% 1-RM, matched for duration of high-intensity interval exercise. Exercise was performed after an overnight fast, with blood samples collected every 30 min, for two hours after exercise. There was a significant interaction between time and intervention for glucose (p = 0.02), which was, on average (mean ± SD), 0.7 ± 0.7 mmol∙L⁻¹ higher following high-intensity interval exercise, as compared to resistance exercise. Cortisol concentration over time was affected by intervention (p = 0.03), with cortisol 70 ± 103 ng∙mL⁻¹ higher (p = 0.015), on average, following high-intensity interval exercise. Resistance exercise did not induce the acute rise in glucose that was induced by high-intensity interval exercise and appears to be an appropriate alternative to positively regulate blood glucose.

Improvements in Muscle Strength Are Associated With Improvements in Walking Capacity in Young Children With Cerebral Palsy: A Secondary Analysis

PURPOSE

To evaluate whether changes in lower-limb muscle strength explain changes in walking capacity during 14-week periods of usual care, power training and follow-up for children with spastic cerebral palsy.

METHODS

Secondary analysis of a previously conducted double-baseline controlled trial of 22 children with spastic cerebral palsy. Generalized estimating equations were used to evaluate the relationships between within-subject changes in isometric muscle strength and walking capacity over 3 periods.

RESULTS

Changes in hip abductor strength were associated with changes in the Muscle Power Sprint Test, changes in gastrocnemius and hip abductor strength were associated with changes in the Shuttle Run Test, and changes in gastrocnemius strength were associated with changes in the 1-minute walk test. All associations supported better walking capacity with increased strength.

CONCLUSION

Walking capacity, especially sprint capacity, can be improved by increasing strength by functional power training in this population.

Intensity Control During Block-Periodized High-Intensity Training: Heart Rate and Lactate Concentration During Three Annual Seasons in World-Class Cross-Country Skiers

Purpose: To describe heart rate (HR) and blood lactate (Bla⁻) responses during high-intensity interval training (HIT) in a long-term block-periodized HIT regimen in world-class cross-country (XC) skiers.

Methods: Data were collected in 14 world-class female XC skiers (aged 25 ± 5 years; body mass, 60.4 ± 6.5 kg; and maximal HR, 194 ± 8 beats · min⁻¹) throughout three entire seasons. The HR and Bla⁻ values were determined at the end of 572 intervals performed during 63 sessions and 17 HIT blocks utilizing different exercise modes: running, running with poles, and skiing (on-snow and roller ski) with classic and skating techniques.

Results: The mean HR was 91 ± 3% of HR_max with a corresponding Bla⁻ of 7.3 ± 2.1 mmol · L⁻¹. The average HR and Bla⁻ values were relatively similar across the different exercise modes, except for a lower HR (~90 vs. 92% of HR_max) for on-snow and roller ski classical skiing and lower Bla⁻ values (5.9 vs. 7.0–7.8 mmol · L⁻¹) for on-snow classical skiing compared to the other modes, both P < 0.05. An increase in HR and Bla⁻ was observed from interval working periods 1 to 3 (90–92% of HR_max and 6.5–7.7 mmol · L⁻¹) and further from 3 to 5 (92–93% of HR_max and 7.7–9.0 mmol · L⁻¹), all P < 0.05.

Conclusions: We describe long-term use of HIT-block periodization among world-class XC skiers who achieved target HR and Bla⁻ levels in all six exercise modes employed. According to athletes and coaches, the key to successful blocks was intensity control to allow for high-quality HIT sessions throughout the entire HIT block.

Comparative study of cardiorespiratory adaptations in elite basketball players of different age groups

BACKGROUND

Systematic training of basketball causes morphological cardiac and cardiorespiratory adaptations. Previous studies have mainly focused either on only cardiac or respiratory changes. However, the extent of these cardiac adaptations and their relationship with aerobic capacity remain unclear in basketball athletes of different ages.

METHODS

Eighty male basketball players participated in the experimental group and 80 healthy and sedentary male individuals served as controls. All participants underwent to athletic history, anthropometric measurements, 12-lead resting electrocardiogram (ECG), echocardiography, resting spirometry and cardiopulmonary exercise stress test.

RESULTS

Left ventricular mass (LVM), left ventricular mass index (LVMI), left ventricular end-diastolic internal dimension (LVIDd), end-diastolic volume (EDV), stroke volume (SV) and interventricular septal thickness at diastole (IVSd) were significantly higher in all groups of athletes compared to controls (P<0.05). End-diastolic volume index (EDVI) was significantly higher only in adult players compared to controls (P<0.05). Posterior wall thickness at diastole (PWd) was significantly greater in groups of children and adult players compared to controls (P<0.05). Maximal oxygen uptake (V̇O<inf>2max</inf>) in relative values was higher in all groups of athletes compared to controls (P<0.05).

CONCLUSIONS

The increased LVM is attributed to concentric hypertrophy. This is further supported by the finding that there was no relationship between V̇O<inf>2max</inf> and echo parameters. The results of the present study indicate that the cardiorespiratory adaptations caused by basketball training are mainly formed at the early age stages without further increase throughout the years of action.

Working out the worries: A randomized controlled trial of high intensity interval training in generalized anxiety disorder

BACKGROUND

Aerobic exercise (AE) demonstrated an overall medium treatment effect in anxiety disorders (AD) but there is evidence for an "intensity-response" relationship. High intensity interval training (HIIT) was highly effective on a range of (mental) health parameters. However, so far no randomised-controlled trial (RCT) investigated the efficacy of HIIT in AD.

METHODS

33 patients with generalized anxiety disorder (GAD) were randomly assigned to 12-day HIIT or a training of lower intensity (LIT). Anxiety, comorbid depression, stress-related bodily symptoms and perceived control over anxiety related stimuli (PC) were assessed at baseline, post-training and 30 days after baseline by using the Penn State Worry Questionnaire (PSWQ), the Hamilton Inventories for Anxiety and Depression (Ham-A, Ham-D), the Screening for Somatoform Symptoms-7 (SOMS-7) and the Anxiety Control Questionnaire (ACQ-R).

RESULTS

Both interventions showed moderate or large effects on all clinical measures. However, effects for HIIT were generally about twice as high as for LIT. PC negatively correlated with GAD severity in the whole sample at baseline but an association of training-induced changes in PC and worrying were exclusively detectable in HIIT.

CONCLUSION

HIIT was highly effective and fast acting in GAD. Therefore, it may complement first-line treatment approaches in this condition.

High-intensity interval training produces a significant improvement in fitness in less than 31 days before surgery for urological cancer: a randomised control trial

OBJECTIVES

To assess the efficacy of high-intensity interval training (HIIT) for improving cardiorespiratory fitness (CRF) in patients awaiting resection for urological malignancy within four weeks.

SUBJECTS/PATIENTS AND METHODS

A randomised control trial of consecutive patients aged (>65 years) scheduled for major urological surgery in a large secondary referral centre in a UK hospital. The primary outcome is change in anaerobic threshold (VO2AT) following HIIT vs. standard care.

RESULTS

Forty patients were recruited (mean age 72 years, male (39): female (1)) with 34 completing the protocol. Intention to treat analysis showed significant improvements in anaerobic threshold (VO2AT; mean difference (MD) 2.26 ml/kg/min (95% CI 1.25-3.26)) following HIIT. Blood pressure (BP) also significantly reduced in following: HIIT (SBP: -8.2 mmHg (95% CI -16.09 to -0.29) and DBP: -6.47 mmHg (95% CI -12.56 to -0.38)). No reportable adverse safety events occurred during HIIT and all participants achieved >85% predicted maximum heart rate during sessions, with protocol adherence of 84%.

CONCLUSIONS

HIIT can improve CRF and cardiovascular health, representing clinically meaningful and achievable pre-operative improvements. Larger randomised trials are required to investigate the efficacy of prehabilitation HIIT upon different cancer types, post-operative complications, socio-economic impact and long-term survival.

Concentrations of Circulating Irisin and Myostatin in Race and Endurace Purebred Arabian Horses-Preliminary Study

Simple Summary

Irisin and myostatin are regulatory proteins produced by muscle cells. The aim of the study was to evaluate the effect of exercise on plasma irisin and myostatin concentrations in horses in different types of training (speed versus endurance). To find out, we tested 20 Arabian horses, submitted to the two different equestrian disciplines, and consequently different training regimes. The first group of horses realized a short-term, high-speed bout of exercise whereas the second group of horses were submitted to long-lasting, endurance effort. The obtained results showed that the single bout of exercise induced an increase in plasma myostatin concentration. Plasma irisin level decreased during the race season in racehorses. This means that irisin and myostatin may play a regulatory role in the maintenance of the energy balance processes.

Abstract

Skeletal muscle is considered to be the largest endocrine organ determining the maintenance of energy homeostasis. Adaptive changes in skeletal muscles in response to physical exercise influence the production as well as secretion of myokines, which are bioactive factors that play a crucial role in energy expenditure processes. The aim of the study was to investigate the impact of two different types of exercise on the circulating level of two of these, myostatin and irisin, in trained horses. Twenty purebred Arabian horses were involved in the study: 10 three-year-old horses trained on the racetrack and 10 endurance horses aged 7.4 ± 1.9 years. The horses from both groups were regularly trained throughout the entire season, during which they also participated in Polish National competitions. To assess the influence of the training sessions on plasma myostatin and irisin concentrations, blood samples taken at rest and 30 min after the end of exercise were analyzed. In the studied horses, the single bout of exercise did not influence plasma irisin but induced an increase in plasma myostatin concentration. In racehorses, plasma irisin concentration decreased with the length of the training season. Plasma myostatin was higher in endurance horses than in three-year-old racehorses. Lack of exercise-induced fluctuation in circulating irisin in studied horses suggests that myostatin released in response to exercise provides a negative feedback signal to irisin release.

The Effect of Endurance Training on Brain-Derived Neurotrophic Factor and Inflammatory Markers in Healthy People and Parkinson's Disease. A Narrative Review

Background: One purpose of the training conducted by people is to lose bodyweight and improve their physical condition. It is well-known that endurance training provides many positive changes in the body, not only those associated with current beauty standards. It also promotes biochemical changes such as a decreased inflammatory status, memory improvements through increased brain-derived neurotrophic factor levels, and reduced stress hormone levels. The positive effects of training may provide a novel solution for people with Parkinson's disease, as a way to reduce the inflammatory status and decrease neurodegeneration through stimulation of neuroplasticity and improved motor conditions. Aim: This narrative review aims to focus on the relationship between an acute bout of endurance exercise, endurance training (continuous and interval), brain-derived neurotrophic factor and inflammatory status in the three subject groups (young adults, older adult, and patients with Parkinson's disease), and to review the current state of knowledge about the possible causes of the differences in brain-derived neurotrophic factor and inflammatory status response to a bout of endurance exercise and endurance training. Furthermore, short practical recommendations for PD patients were formulated for improving the efficacy of the training process during rehabilitation. Methods: A narrative review was performed following an electronic search of the database PubMed/Medline and Web of Science for English-language articles between January 2010 and January 2020. Results: Analysis of the available publications with partial results revealed (1) a possible connection between the brain-derived neurotrophic factor level and inflammatory status, and (2) a more beneficial influence of endurance training compared with acute bouts of endurance exercise. Conclusion: Despite the lack of direct evidence, the results from studies show that endurance training may have a positive effect on inflammatory status and brain-derived neurotrophic factor levels. Introducing endurance training as part of the rehabilitation in Parkinson's disease might provide benefits for patients in addition to pharmacological therapy supplementation.

Predictive Performance Models in Long-Distance Runners: A Narrative Review

Physiological variables such as maximal oxygen uptake (VO₂max), velocity at maximal oxygen uptake (vVO₂max), running economy (RE) and changes in lactate levels are considered the main factors determining performance in long-distance races. The aim of this review was to present the mathematical models available in the literature to estimate performance in the 5000 m, 10,000 m, half-marathon and marathon events. Eighty-eight articles were identified, selections were made based on the inclusion criteria and the full text of the articles were obtained. The articles were reviewed and categorized according to demographic, anthropometric, exercise physiology and field test variables were also included by athletic specialty. A total of 58 studies were included, from 1983 to the present, distributed in the following categories: 12 in the 5000 m, 13 in the 10,000 m, 12 in the half-marathon and 21 in the marathon. A total of 136 independent variables associated with performance in long-distance races were considered, 43.4% of which pertained to variables derived from the evaluation of aerobic metabolism, 26.5% to variables associated with training load and 20.6% to anthropometric variables, body composition and somatotype components. The most closely associated variables in the prediction models for the half and full marathon specialties were the variables obtained from the laboratory tests (VO₂max, vVO₂max), training variables (training pace, training load) and anthropometric variables (fat mass, skinfolds). A large gap exists in predicting time in long-distance races, based on field tests. Physiological effort assessments are almost exclusive to shorter specialties (5000 m and 10,000 m). The predictor variables of the half-marathon are mainly anthropometric, but with moderate coefficients of determination. The variables of note in the marathon category are fundamentally those associated with training and those derived from physiological evaluation and anthropometric parameters.

Effect of High-Intensity Interval Training Versus Small-Sided Games Training on Sleep and Salivary Cortisol Level

PURPOSE

The authors compared sleep quality and salivary cortisol concentration after high-intensity interval training (HIIT) and small-sided games (SSGs) performed at the habitual training time in nonprofessional male soccer players.

METHODS

A total of 32 players (age = 24 [6] y, height = 1.77 [0.06] m, and body mass = 75 [12] kg) were randomized into an HIIT group or an SSG group. Actual sleep time, sleep efficiency (SE), sleep latency, immobility time (IT), moving time (MT), and fragmentation index were monitored using actigraphy before (PRE) and 2 nights after (POST 1 and POST 2) the training session. Salivary cortisol levels were measured before (PRE) and after (POST) training. Cortisol awakening response was evaluated.

RESULTS

Significant intragroup differences in the HIIT group were noted for actual sleep time (P < .0001), SE (P < .0001), sleep latency (P = .047), IT (P < .0001), MT (P < .0001), and fragmentation index (P < .0001) between PRE and POST 1 and for SE (P = .035), IT (P = .004), MT (P = .006), and fragmentation index (P = .048) between PRE and POST 2. Intergroup differences for actual sleep time (P = .014), SE (P = .048), IT (P < .0001), and MT (P = .046) were observed between the HIIT and the SSGs group at POST 1 were detected. Significant intragroup variations were observed in PRE and POST salivary cortisol levels (P < .0001 for HIIT; P = .0003 for SSGs) and cortisol awakening response (P < .0001 for HIIT; P < .0001 for SSGs). Significant intergroup differences between the HIIT and the SSGs group were found at POST (P < .0001) and in cortisol awakening response (P = .017).

CONCLUSIONS

Changes in actigraphy-based sleep parameters and salivary cortisol levels were greater after an acute session of HIIT than SSGs in this sample of nonprofessional male soccer players.

High intensity interval training protects from Post Traumatic Stress Disorder induced cognitive impairment

This study aimed to show the possible protective effects of high intensity interval training (HIIT) in PTSD-induced rats and probable underlying mechanisms. Female rats (n = 44) were separated as; Sedentary (SED), moderate intensity continuous training (MICT), HIIT groups. Then the groups were divided into subgroups according to PTSD induction (n = 6-8/group). Exercise groups performed HIIT or MICT for 6 weeks. On the fifth week, PTSD was induced by single prolonged stress protocol. Cognitive functions were evaluated by object recognition, anxiety levels by hole-board and elevated plus maze, and fear conditioning by passive avoidance tests. Following decapitation, malondialdehyde (MDA), glutathione (GSH), luminol and lucigenin chemiluminescence levels, and myeloperoxidase (MPO), superoxide dismutase (SOD) and catalase (CAT) activities were measured, and histopathological damage was evaluated. The data was analyzed by one-way ANOVA. Cognitive decline and aggravated anxiety levels in SED + PTSD group were improved in both PTSD-induced exercise groups (p < 0.05-0.001). The increased chemiluminescence levels, MPO activity and histological damage were depressed in both PTSD-induced exercise groups (p < 0.05-0.001). The risen MDA levels in SED + PTSD group were suppressed only in HIIT + PTSD group (p < 0.01-0.001). The decreased GSH levels were increased by MICT (p < 0.05-0.001), and CAT and SOD activities were improved via HIIT (p < 0.05). Compared to SED group, latency was decreased in SED + PTSD (p < 0.05-0.01) group. Neuronal damage scores were alleviated in both PTSD-induced exercise groups (p < 0.001). PTSD-induced memory decline was protected by both of the exercise models however more effectively by HIIT via decreasing oxidative stress, anxiety levels and by improving antioxidant capacity as a protective system for neuronal damage.

The Application of Critical Power, the Work Capacity above Critical Power (W'), and its Reconstitution: A Narrative Review of Current Evidence and Implications for Cycling Training Prescription

The two-parameter critical power (CP) model is a robust mathematical interpretation of the power–duration relationship, with CP being the rate associated with the maximal aerobic steady state, and W′ the fixed amount of tolerable work above CP available without any recovery. The aim of this narrative review is to describe the CP concept and the methodologies used to assess it, and to summarize the research applying it to intermittent cycle training techniques. CP and W′ are traditionally assessed using a number of constant work rate cycling tests spread over several days. Alternatively, both the 3-min all-out and ramp all-out protocols provide valid measurements of CP and W′ from a single test, thereby enhancing their suitability to athletes and likely reducing errors associated with the assumptions of the CP model. As CP represents the physiological landmark that is the boundary between heavy and severe intensity domains, it presents several advantages over the de facto arbitrarily defined functional threshold power as the basis for cycle training prescription at intensities up to CP. For intensities above CP, precise prescription is not possible based solely on aerobic measures; however, the addition of the W′ parameter does facilitate the prescription of individualized training intensities and durations within the severe intensity domain. Modelling of W′ reconstitution extends this application, although more research is needed to identify the individual parameters that govern W′ reconstitution rates and their kinetics.

Performing Soccer-Specific Training With Blood Flow Restriction Enhances Physical Capacities in Youth Soccer Players

Hosseini Kakhak, SA, Kianigul, M, Haghighi, AH, Nooghabi, MJ, and Scott, BR. Performing soccer-specific training with blood flow restriction enhances physical capacities in youth soccer players. J Strength Cond Res XX(X): 000-000, 2020-This study investigated the effect of soccer training with blood flow restriction (BFR) on physical performance in youth athletes. Nineteen semiprofessional soccer players were randomly assigned to either normal soccer training (ST; n = 9) or soccer training with BFR (STBFR; n = 10). Both groups performed identical activities during a 6-week preseason training phase, either with or without lower limb BFR. Training included soccer-specific drills, small-sided games, plyometrics, and continuous running. Before and after the intervention, players were assessed for leg extension strength and endurance, countermovement jump performance, 40-yd sprint time, change-of-direction (COD) ability, aerobic endurance, and soccer-specific endurance (while dribbling a ball). Significantly larger improvements were observed in the STBFR compared with the ST group for tests of muscular endurance (74.8 ± 34.1% vs. 4.0 ± 14.6%), COD (8.1 ± 3.7% vs. 2.8 ± 4.7%), and aerobic (54.1 ± 19.6% vs. 24.7 ± 27.2%) and soccer-specific endurance (58.4 ± 19.6% vs. 22.7 ± 10.2%). Main effects for time were observed for maximal strength, jumping, and sprinting performance (p < 0.001) but with no group and time interaction. These findings demonstrate that team sport training with BFR can enhance physical qualities that are related to performance in youth soccer players. This application of BFR may improve the adaptive responses of muscles, without having to dedicate additional training time to muscular qualities.

The importance of the verification phase following an incremental exercise to ensure maximum oxygen consumption

BACKGROUND

The purpose of this study was to analyze cardiac output (Qc), stroke volume (SV), heart rate (HR), and arterio-venous O<inf>2</inf> difference (a-vO<inf>2diff</inf>) responses throughout a graded exercise test (GXT) and verification phase (VP) to examine whether SV decrement during the GXT is a main factor for underestimation of the maximal O<inf>2</inf> uptake (V̇O<inf>2max</inf>), or not.

METHODS

Seven well-trained male cyclists volunteered for this study (V̇O<inf>2max</inf>: 61.7±6.13 mL∙min^-1∙kg^-1). Following submaximal tests, participants were asked to perform GXT until exhaustion. Then, multisession verifications were performed on different days using ±3% constant work rates. The highest 30-second mean of V̇O<inf>2</inf> was considered as the V̇O<inf>2max</inf> and corresponding external power as peak power output (PPO). The Qc, SV, HR, and a-vO<inf>2diff</inf> responses were evaluated at both GXT and VP by nitrous-oxide rebreathing method. After repeated-measures analyses, possible significant differences were investigated by LSD/Wilcoxon.

RESULTS

It was shown that the HR and a-vO<inf>2diff</inf> reached their potentially highest values at the end of the both GXT and VP (192.9±8.8 vs. 190.7±7.9 bpm; 17.1±1.6 vs. 16.9±1.1%, respectively; P>0.05); however, SV (128.8±11.2 vs. 137.3±11.2 mL; P=0.029) and Qc (24.8±2.02 vs. 26.2±2.71 L·min^-1; P=0.046) were lower at GXT when compared to the VP. V̇O<inf>2</inf> means were, therefore, higher in VP when compared to the GXT (61.7±6.13 vs. 59.1±6.2 mL∙min^-1∙kg^-1; P=0.041).

CONCLUSIONS

The GXT provided only a peak V̇O<inf>2</inf> but not the V̇O<inf>2max</inf>. Consequently, the real V̇O<inf>2max</inf> and PPO could be provided by only VP administrations. This is likely to result from the lower Qc and SV responses observed from a prolonged incremental test protocol when compared to short bouts of constant work rate trials.

Efficacy of a Six-Week Dispersed Wingate-Cycle Training Protocol on Peak Aerobic Power, Leg Strength, Insulin Sensitivity, Blood Lipids and Quality of Life in Healthy Adults

The aim of this study was to evaluate the efficacy of a six-week dispersed Wingate Anaerobic test (WAnT) cycle exercise training protocol on peak aerobic power (VO_2peak), isokinetic leg strength, insulin sensitivity, lipid profile and quality of life, in healthy adults. Methods: We conducted a match-controlled cohort trial and participants were assigned to either the training (intervention, INT, N = 16) or non-training (control, CON, N = 17) group. INT performed 30-s WAnT bouts three times a day in the morning, afternoon and evening with each bout separated by ~4 h of rest, performed for 3 days a week for 6 weeks. Criterion measures of peak oxygen uptake (VO_2peak), leg strength, insulin markers such as homeostatic model assessment (HOMA) and quantitative insulin-sensitivity check index (QUICKI), blood lipids profile and health-related quality of life (HRQL) survey were assessed before and after 6 weeks in both groups. Results: Absolute VO_2peak increased by 8.3 ± 7.0% (p < 0.001) after INT vs. 0.9 ± 6.1% in CON (p = 0.41) group. Maximal voluntary contraction at 30°·s^-1 of the dominant lower-limb flexors in INT increased significantly post-training (p = 0.03). There were no changes in the INT individuals' other cardiorespiratory markers, HOMA, QUICKI, blood lipids, and HRQL measures (all p > 0.05) between pre- and post-training; but importantly, no differences were observed between INT and CON groups (all p > 0.05). Conclusions: The results indicate that 6 weeks of dispersed sprint cycle training increased cardiorespiratory fitness and dynamic leg strength but had minimal impact on insulin sensitivity, blood lipids and quality of life in the exercising individuals.