Cardiorespiratory and metabolic characteristics of detraining in humans

Symptomatic bradyarrhythmias in the athlete-Underlying mechanisms and treatments

Bradyarrhythmias including sinus bradycardia and atrioventricular (AV) block are frequently encountered in endurance athletes especially at night. While these are well tolerated by the young athlete, there is evidence that generally from the fifth decade of life onward, such arrhythmias can degenerate into pathological symptomatic bradycardia requiring pacemaker therapy. For many years, athletic bradycardia and AV block have been attributed to high vagal tone, but work from our group has questioned this widely held assumption and demonstrated a role for intrinsic electrophysiological remodeling of the sinus node and the AV node. In this article, we argue that bradyarrhythmias in the veteran athlete arise from the cumulative effects of exercise training, the circadian rhythm and aging on the electrical activity of the nodes. We consider contemporary strategies for the treatment of symptomatic bradyarrhythmias in athletes and highlight potential therapies resulting from our evolving mechanistic understanding of this phenomenon.

Can period-related symptoms predict menstrual manipulation among Australian female cyclists?

This study explored the extent of menstrual manipulation and its associated impact on period-related symptoms and training disruptions in Australian Female Cyclists. 205 female cyclists, from recreational to elite level, participated in an online "Female Cyclist Questionnaire (FCQ)". The FCQ utilised a series of validated questionnaires to obtain demographic information and menstrual function of the respondents, and to investigate their menstrual manipulation habits and perceptions on how their period-related symptoms affected their well-being, mood, energy and training tolerance. More than 80% of the cyclists reported that their period-related symptoms impacted upon training and 41% made training adjustments based on these symptoms. Two-thirds of respondents thought their training should be phase-controlled yet only half discussed their hormonal cycles with their coaches. Menstrual manipulation was predicted by reduced "workout tolerance" in these cyclists (odds ratio = 0.632). Half of the respondents reported compromised ability to tolerate high-intensity interval training with period-related symptoms. Period pain, increased irritability, lower energy levels and more sugar cravings were commonly reported but did not predict menstrual manipulation. The data indicated that period-related symptoms are present in Australian female cyclists across all levels of participation. However, the perceived impact to training and subsequent behavioural changes varied among individuals.

Back to 'normal'? BMI, physical fitness and health-related quality of life of children from North East England before, during and after the COVID-19 lockdowns

We assessed whether changes in children's body mass index (BMI), physical fitness and health-related quality of life observed post-2020 United Kingdom COVID-19 lockdown remained 12 and 18 months later. Twenty-metre shuttle run test (20mSRT), handgrip strength, standing broad jump, sit-and-reach, height, body mass, and health-related quality of life (Kidscreen27 questionnaire) were measured in 90 children (8-9 years) during October 2019 ("T0"), November 2020 ("T1"), November 2021 ("T2") and June 2022 ("T3"). Mixed-effects models showed age- and sex-normalised BMI increased from T0 (mean: 0.71) to T1 (0.97), remaining elevated at T2 (0.95) and T3 (0.89). Decreases in 20mSRT performance were observed from T0 (22.0) to T1 (19.3), then increased at T2 (23.5) and T3 (28.3). Standing broad jump and handgrip strength increased over time. The proportion of children with overweight/obesity increased from T0 (32%) to T3 (48%). Health-related quality of life decreased for "Physical Wellbeing" yet increased for "Autonomy & Parents". Our findings highlight that lockdowns may have had lasting implications for children's health, and the urgent need to reduce overweight and obesity in North East England. Improving health and fitness behaviours to maximise long-term health outcomes and build resilience to future emergencies and disruptions to health behaviours is also paramount.

Supervised Offseason Training Programs are able to mitigate the Effects of Detraining in Youth Men Soccer Players Physical Fitness: A Randomized Parallel Controlled Study

This study aimed to analyze the effects of three off-season training programs on the aerobic capacity, countermovement jump (CMJ), and linear sprint performance of young male soccer players. The study employed a randomized multi-arm design, consisting of three experimental groups: i) a high-intensity interval training (HIIT) group; (ii) a plyometric jump training (PJT) group; and (iii) a HIIT+PJT group; and an inactive control group. Fifty-eight under-19 male soccer players (aged 17.6 ±0.6 years) were randomly assigned to participate in a 3-week offseason training program exclusively performing HIIT, PJT, or a combination of both, while the fourth group remained inactive. Players underwent assessments twice, using the Yo-Yo Intermittent Recovery Test - Level 1 (YYIRT), CMJ, and 30-meter linear sprint. Significant interactions between time and groups were found in CMJ (p<0.001), YYIRT (p<0.001), and 30-m sprint (p<0.001). Group*time interaction revealed that the control group was significantly different from HIIT (p<0.001), PJT (p<0.001), and HIIT+PJT (p<0.001) considering the CMJ. Moreover, the control group was significantly different from HIIT (p=0.037) in YYIRT. Finally, the control group was significantly different from HIIT (p=0.024), PJT (p<0.001), and HIIT+PJT (p=0.021) considering the 30-m sprint. In conclusion, off-season training programs are effective in significantly reducing declines in CMJ and sprint performance compared to maintaining training cessation. However, in the YYIRT, only HIIT seems to be significantly superior to maintaining inactivity. To mitigate aerobic performance declines, incorporating HIIT sessions twice weekly during the offseason is advisable. To enhance or maintain jump performance, integrating at least one session of PJT weekly is beneficial.

Exercise for falls prevention in aged care: systematic review and trial endpoint meta-analyses

BACKGROUND

There is strong evidence that exercise reduces falls in older people living in the community, but its effectiveness in residential aged care is less clear. This systematic review examines the effectiveness of exercise for falls prevention in residential aged care, meta-analysing outcomes measured immediately after exercise or after post-intervention follow-up.

METHODS

Systematic review and meta-analysis, including randomised controlled trials from a Cochrane review and additional trials, published to December 2022. Trials of exercise as a single intervention compared to usual care, reporting data suitable for meta-analysis of rate or risk of falls, were included. Meta-analyses were conducted according to Cochrane Collaboration methods and quality of evidence rated using the Grading of Recommendations Assessment, Development and Evaluation approach.

RESULTS

12 trials from the Cochrane review plus 7 new trials were included. At the end of the intervention period, exercise probably reduces the number of falls (13 trials, rate ratio [RaR] = 0.68, 95% confidence interval [CI] = 0.49-0.95), but after post-intervention follow-up exercise had little or no effect (8 trials, RaR = 1.01, 95% CI = 0.80-1.28). The effect on the risk of falling was similar (end of intervention risk ratio (RR) = 0.84, 95% CI = 0.72-0.98, 12 trials; post-intervention follow-up RR = 1.05, 95% CI = 0.92-1.20, 8 trials). There were no significant subgroup differences according to cognitive impairment.

CONCLUSIONS

Exercise is recommended as a fall prevention strategy for older people living in aged care who are willing and able to participate (moderate certainty evidence), but exercise has little or no lasting effect on falls after the end of a programme (high certainty evidence).

The Impacts of Supervised Exercise Intervention on Tobacco Withdrawal Symptoms

This study examined a supervised moderate-intensity aerobic exercise programme's effectiveness in regulating the Tobacco Withdrawal Symptoms (TWS) during temporary abstinence. This was a single group, pre and post-quasi intervention study. Thirty daily smokers participated in an 8-week supervised moderate-intensity aerobic exercise programme. We assessed the TWS, smoking urge, mood and stress-pleasure related hormonal variables after the aerobic exercise intervention. The measurements were conducted after overnight abstinence at baseline, post-intervention (at week-8) and post-detraining (at week-10). TWS components, smoking urge and mood were found to improve. For hormonal variables, cortisol and beta-endorphin except adrenaline showed insignificant changes at post-intervention and de-training. The findings suggest moderate-intensity exercise might help in reducing withdrawal symptoms and its adverse effects. Thus, exercise is an effective adjunct treatment in a smoking cessation programme.

Resting heart rate is a population-level biomarker of cardiorespiratory fitness: The Fenland Study

INTRODUCTION

Few large studies have evaluated the relationship between resting heart rate (RHR) and cardiorespiratory fitness. Here we examine cross-sectional and longitudinal relationships between RHR and fitness, explore factors that influence these relationships, and demonstrate the utility of RHR for remote population monitoring.

METHODS

In cross-sectional analyses (The UK Fenland Study: 5,722 women, 5,143 men, aged 29-65y), we measured RHR (beats per min, bpm) while seated, supine, and during sleep. Fitness was estimated as maximal oxygen consumption (ml⋅min-1⋅kg-1) from an exercise test. Associations between RHR and fitness were evaluated while adjusting for age, sex, adiposity, and physical activity. In longitudinal analyses (6,589 participant subsample), we re-assessed RHR and fitness after a median of 6 years and evaluated the association between within-person change in RHR and fitness. During the coronavirus disease-2019 pandemic, we used a smartphone application to remotely and serially measure RHR (1,914 participant subsample, August 2020 to April 2021) and examined differences in RHR dynamics by pre-pandemic fitness level.

RESULTS

Mean RHR while seated, supine, and during sleep was 67, 64, and 57 bpm. Age-adjusted associations (beta coefficients) between RHR and fitness were -0.26, -0.29, and -0.21 ml⋅kg-1⋅beat-1 in women and -0.27, -0.31, and -0.19 ml⋅kg-1⋅beat-1 in men. Adjustment for adiposity and physical activity attenuated the RHR-to-fitness relationship by 10% and 50%, respectively. Longitudinally, a 1-bpm increase in supine RHR was associated with a 0.23 ml⋅min-1⋅kg-1 decrease in fitness. During the pandemic, RHR increased in those with low pre-pandemic fitness but was stable in others.

CONCLUSIONS

RHR is a valid population-level biomarker of cardiorespiratory fitness. Physical activity and adiposity attenuate the relationship between RHR and fitness.

Impact of the COVID-19 Pandemic Hiatus From Sports Activities on Injuries Observed Among Division I NCAA Athletes

Background

The coronavirus disease 2019 (COVID-19) pandemic significantly disrupted athletic activities, including those in the Pacific 12 (Pac-12) Conference of the National Collegiate Athletic Association. It is currently unknown how the disruption in training and competition impacted athletes' risk of injury upon resumption of activities.

Purpose

To describe and compare the rate, timing, mechanism, and severity of injuries among collegiate athletes across multiple sports in the Pac-12 Conference before and after the COVID-19 pandemic-associated hiatus of intercollegiate athletic activities.

Study Design

Descriptive epidemiology study.

Methods

Descriptive and injury data among intercollegiate athletes from both the season before the hiatus and the season after the hiatus were acquired from the Pac-12 Health Analytics Program database. Injury elements (timing of injury onset, injury severity, mechanism, recurrence, outcome, need for procedural intervention, and event segment during which the injury took place) were compared by time using the chi-square test and a multivariate logistic regression model. Subgroup analyses were performed on knee and shoulder injuries among athletes participating in sports with traditionally high rates of knee and shoulder injuries.

Results

A total of 12,319 sports-related injuries across 23 sports were identified, with 7869 pre-hiatus injuries and 4450 post-hiatus injuries. There was no difference in the overall incidence of injury between the pre-hiatus and post-hiatus seasons. However, the proportion of noncontact injuries was higher in the post-hiatus season for football, baseball, and softball players, and the proportion of nonacute injuries in the post-hiatus season was higher among football, basketball, and rowing athletes. Finally, the overall proportion of injuries sustained by football players in the final 25% of competition or practice was higher in the post-hiatus season.

Conclusion

Athletes competing in the post-hiatus season were observed to have higher rates of noncontact injuries and injuries sustained in the final 25% of competition. This study demonstrates that the COVID-19 pandemic has had varied effects on athletes from different sports, suggesting that many factors must be considered when designing return-to-sports programs for athletes after an extended absence from organized training.

Injury Characteristics among Young Adults during and Immediately after the COVID-19 Lockdown

The lockdown due to the COVID-19 pandemic inherently changed people’s lifestyles. Forty-eight days of isolation led to worsening physical fitness in addition to the development of other unhealthy habits. The aim of this study was to describe sport-related injuries in the active general population. Physical therapy centres and sports medicine clinics were contacted via e-mail, seeking patients who had sustained an injury during or immediately (up to two weeks) after the lockdown. Patients who agreed to participate completed an online survey that followed the International Olympic Committee Statement. The questionnaire focused on physical exercise habits, type of injury, location and tissue affected. A total of 51 females and 67 males (30.5, SD = 8.8 years) participated in the study. Eighty percent of the participants performed aerobic training sessions, while the rest dedicated their workouts to strength training. Two in every three injuries were located in the lower limbs, and 80% affected the musculoskeletal tissue. Of all the injuries recorded, 67% occurred during the first week after lockdown. The number of aerobic exercise sessions was positively correlated with lower limb injuries (χ2 = 17.12, p < 0.05). Exercise habits should be considered when planning to return to a sport after a period of confinement to avoid injury.

Analysis of the Sustainability of Long-Term Detraining Caused by COVID-19 Lockdown: Impact on the Maximal Aerobic Speed of Under-16 Soccer Players

This retrospective cohort study aimed to analyze the effect of a 9-week detraining caused by COVID-19 lock-down on the maximal aerobic speed (MAS) of youth soccer players. The study included twenty-two under-16 male players competing at the national league level (15.4 ± 0.7 years old) who were analyzed pre and post the detraining period. The MAS was estimated using the Bronco’s test. Moreover, the self-regulated physical exercise performed by the players during the lockdown was monitored using a questionnaire. Considering the training volume per week, the players were grouped into those working more (>180 min/week) and those working less (<180 min/week) during the lockdown. Within-group changes revealed no significant differences (p = 0.122; d = 0.381) in the group that self-trained less than 180 min/week started (pre-lockdown) at 3.97 ± 0.29 m/s and ended (post-lockdown) at 3.85 ± 0.34 m/s, corresponding to a decrease of 3.02%. For those who self-trained more than 180 min/week during the lockdown, they started with 4.33 ± 0.28 m/s and decreased by 1.62% for 4.26 ± 0.28 m/s (p = 0.319; d = 0.250). The team as a whole (pooled data, all players included) decreased 2.27% from 4.15 ± 0.34 to 4.06 ± 0.37 m/s (p = 0.077; d = 0.321). Between group analysis revealed that the group of players that trained more than 180 min/weeks were significantly better than players working below 180 min/week in both pre-lockdown moment (+9.01%; p = 0.007; d = 1.263) and post-lockdown moment (10.6%; p = 0.006; d = 1.323). Home-based training can be a good strategy to mitigate the detraining effects caused by a lockdown.

Vascular alterations among male elite athletes recovering from SARS-CoV-2 infection

SARS-CoV-2 may affect the cardiovascular system and vascular impairment has been reported in healthy young adults recovering from COVID-19. However, the impact of SARS-CoV-2 infection on the vascular function of elite athletes is unknown. We examined 30 healthy male elite athletes (age 25.8 ± 4.6 years) pre-season and at a 6-month follow-up (182 ± 10 days). Vascular function and central blood pressure were calculated using transfer function-based analysis of peripheral arterial waveforms obtained by oscillometry. We performed a two-way repeated-measures ANOVA on the biomarker data, with SARS-CoV-2 status as the between-groups factor and time as the within-groups factor. Subjects who tested positive for SARS-CoV-2 were studied 18 ± 4 days after their positive testing date at follow-up. Of 30 athletes, 15 tested positive for SARS-CoV-2 after the first examination and prior to the follow-up. None had severe COVID-19 or reported any persisting symptoms. The results of the two-way repeated measures ANOVA revealed that there was no significant main effect of COVID-19 on any of the investigated biomarkers. However, there was a significant interaction between the effects of SARS-CoV-2 exposure and time on augmentation index (Aix) (p = 0.006) and augmentation index normalized to a heart rate of 75 beats per minute (Aix@75), (p = 0.0018). The observation of an interaction effect on Aix and Aix@75 in the absence of any main effect indicates a cross-over interaction. Significant vascular alterations in male elite athletes recovering from COVID-19 were observed that suggest vascular impairment. Whether these alterations affect athletic performance should be evaluated in future studies.

Effects of 3 months of detraining following cardiac rehabilitation in patients with atrial fibrillation

Background

Atrial fibrillation negatively impacts physical fitness and health-related quality of life. We recently showed that 3 months of physiotherapist-led exercise-based cardiac rehabilitation improves physical fitness and muscle function in elderly patients with permanent atrial fibrillation and concomitant diseases. Little is, however, known about the consequences for physical fitness, physical activity level, and health-related quality of life after ending the rehabilitation period.

Methods

Prospective 3 months follow-up study of 38 patients out of 40 eligible (10 women) who, as part of a randomized controlled trial, had completed a 3 months physiotherapist-led cardiac rehabilitation resulting in improved physical fitness,. In the current study, the participants were instructed to refrain from exercise for 3 months after completion of the rehabilitation period. Primary outcome measure was physical fitness measured as highest achieved workload using an exercise tolerance test. Secondary outcome measures were muscle function (muscle endurance tests), physical activity level (questionnaire and accelerometer), and health-related quality of life, (Short Form-36), as in the preceding intervention study. We used the Wilcoxon Signed Rank test to analyse differences between the end of rehabilitation and at follow-up. The effect size was determined using Cohen’s d .

Results

Exercise capacity and exercise time significantly decresead between end of rehabilitation and at follow-up (p < .0001 for both). A significant reduction in shoulder flexion repetitions (p = .006) was observed as well as reduced health-related quality of life in the Short Form-36 dimensions Physical Function (p = .042), Mental Health (p = .030), and Mental Component Score (p = .035). There were, however, no changes regarding objective and subjective physical activity measurements.

Conclusion

In older patients with permanent atrial fibrillation, previously achieved improvements from physiotherapist-led exercise-based cardiac rehabilitation in physical fitness and muscle function were lost, and health-related quality of life was impaired after ending the rehabilitation period. A strategy for conserving improvements after a rehabilitation period is essential.

Effects of high intensity interval training on sustained reduction in cardiometabolic risk associated with overweight/obesity. A randomized trial

Background

Considering the potential greater cardiocirculatory effects of high intensity interval training (HIIT), we hypothesized that a 2-month supervised high volume short interval HIIT would induce greater improvements in CRF and cardiometabolic risk and increase long-term maintenance to physical activity compared to isocaloric moderate intensity continuous training (MICT) in overweight/obesity.

Methods

Sixty (19 females) subjects with overweight/obesity were randomized to three training programs (3 times/week for 2 months): MICT (45 min, 50% peak power output-PPO), HIIT (22 × 1-min cycling at 100% PPO/1-min passive recovery) and HIIT-RM (RM: recovery modulation, i.e. subjects adjusted passive recovery duration between 30s and 2 min). After the intervention, participants no longer benefited from supervised physical activity and were instructed to maintain the same exercise modalities on their own. We assessed anthropometrics, body composition, CRF, fat oxidation, lipid profile, glycemic balance, low-grade inflammation, vascular function, spontaneous physical activity and motivation for eating at three time points: baseline (T0), 4 days after the end of the 2-month supervised training program (T2) and 4 months after the end of the training program (T6).

Results

HIIT/HIIT-RM induced greater improvement in VO_2peak (between +14% and +17%), power output at ventilatory thresholds and at maximal fat oxidation rate (+25%) and waist circumference (−1.53 cm) compared to MICT and tended to decrease insulin resistance. During the four-month follow-up period during which exercise in autonomy was prescribed, HIIT induced a greater preservation of CRF, decreases in total and abdominal fat masses and total cholesterol/HDL.

Conclusion

We have shown greater short-term benefits induced by a high volume short interval (1 min) HIIT on cardiorespiratory fitness and cardiometabolic risk over an isocaloric moderate intensity continuous exercise in persons with overweight/obesity. We also showed greater long-term effects (i.e. after 4 months) of this exercise modality on the maintenance of CRF, decreases in total and abdominal fat masses and total cholesterol/HDL.

A Coaching Perspective on Modern Training Metrics and Return from Injury and Illness

Guiding cyclists in their return from illness and injury can be managed in many ways. Understanding how cyclists use power-derived training metrics can give care providers a common language to aid in this return. A general understanding of these metrics may be used to monitor cyclists for signs of nonfunctional overreaching or overtraining. Understanding aspects of training and detraining, particularly hematological, is helpful in communicating fitness expectations. Three populations of cyclists are discussed in terms of their expected knowledge of these metrics, typical training volume and intensity, and relationship with a coach or coaches.

Effect of Training and Detraining in the Components of Physical Fitness in People Living With HIV/AIDS

The aim of the study was to evaluate the effect of training and detraining on the physical fitness components of people living with HIV/AIDS (PLHA). The study was characterized as experimental with a sample composed of 21 people divided into two groups: 11 volunteers (PLHA, 46.9 ± 8.0 years, 63.8 ± 12.7 kg, 161.7 ± 8.7 cm, 7 men, and 4 women), using antiretroviral therapy (ART) and 10 people without HIV/AIDS in the control group (CG, 43.8 ± 13.8 years, 75.2 ± 11.2 kg, 163.3 ± 7.8 cm, 3 men, and 7 women), with the same average age and level of physical activity. The intervention, applied to both groups, consisted of combined training for 15 weeks, followed by detraining for 5 weeks. Before and after the training and detraining period the following parameters were evaluated: body composition by dual energy radiological absorptiometry (DXA), cardiorespiratory fitness by ergospirometer, and strength of upper and lower limbs by isometric dynamometer. The results show the effect of the intervention moments on the strength and oxygen consumption variables (time factor), considering the two study groups. Regarding the analysis of the interaction (group vs. time), there was a significant effect on the isometric extension strength of the left (p = 0.019) and right (p = 0.030) knees, with training (left: 10.4%; right: 12.4%) and detraining (left: −10.8%; right: −12.1%) effect in PLHA, when compared with the control group (left: 8.1 and 3.9%, respectively; right: 11.5 and −0.2%, respectively). In addition, there was a significant interaction on ventilatory threshold 1 (p = 0.002), indicating a significantly greater increase with training (27.3%) and decrease with detraining (−22.7%) in the PLHA group compared with the Control group (19.9 and −6.7%, respectively). In conclusion, combined training and the subsequent period of detraining caused similar responses in body composition, isometric strength, and cardiorespiratory fitness of PLHA and CG, except for the extensor strength of the lower limbs and ventilatory threshold 1, which presented positive effects on training and negative effects on detraining for PLHA.

Clinical Trial Registration:www.ClinicalTrials.gov, identifier NCT03075332.

Training Session and Detraining Duration Affect Lower Limb Muscle Strength Maintenance in Middle-Aged and Older Adults: A Systematic Review and Meta-Analysis

Muscle strength after detraining is still higher than the level before training, which is an important issue for middle-aged and older adults. The purpose of the present study was to examine the effects of detraining duration (DD), resistance training duration (RTD), and intensity on the maintenance of resistance training (RT) benefits after detraining in middle-aged and older adults. A systematic search yielded 15 randomized control trails (n = 383) eligible for inclusion. The results showed that RTD ≥ 24 weeks and DD ≥ RTD, the RT benefits were still significantly maintained even with medium and low intensity (standardized mean difference = 1.16, 95% confidence interval, CI [0.38, 1.94], p = .004). When RTD < 24 weeks and DD ≤ RTD, only the high-intensity groups maintained the RT benefits (DD, 4-6 weeks: standardized mean difference = 0.71, 95% CI [0.34, 1.08], p = .0002; DD 8-16 weeks: standardized mean difference = 1.35, 95% CI [0.66, 2.04], p = .0001). However, when DD > RTD, the RT benefits were not maintained even with high intensity. In summary, when RTD was less than 24 weeks, RTD > DD was an important factor in maintaining muscle strength.

Impact of COVID-19 on Swimming Training: Practical Recommendations during Home Confinement/Isolation

The COVID-19 pandemic has had severe effects on communities globally, leading to significant restrictions on all aspects of society, including in sports. Several significant decisions were made to postpone or cancel major swimming events by FINA (Fédération Internationale de Natation). Swimmers were no longer allowed to continue their usual training in swimming pools and were confined to their homes. These unusual circumstances may represent a good opportunity to strengthen different areas of swimmer preparation and potentially enhance performance when resuming regular aquatic training. We searched major databases for relevant information, and the present article provides practical information on home-based training for swimmers of all ages. The COVID-19 crisis and its consequences on the swimming community have created a myriad of challenges for swimmers around the world, including maintaining their fitness level and preparing to return optimally and safely to pool training and competitions. Unfortunately, the mental consequences that might arise after the pandemic may also have an impact. We strongly recommend encouraging the swimmers to consider quarantine as an opportunity for development in specific areas of preparation and learn how to best cope with this special situation of self-isolation and/or "physical distancing" for their mental health and in case a similar situation is faced again in the future.

Maintaining Physical Performance: The Minimal Dose of Exercise Needed to Preserve Endurance and Strength Over Time

ABSTRACT

Maintaining physical performance: the minimal dose of exercise needed to preserve endurance and strength over time, Spiering, BA, Mujika, I, Sharp, MA, and Foulis, SA. J Strength Cond Res 35(5): 1449-1458, 2021-Nearly every physically active person encounters periods in which the time available for exercise is limited (e.g., personal, family, or business conflicts). During such periods, the goal of physical training may be to simply maintain (rather than improve) physical performance. Similarly, certain special populations may desire to maintain performance for prolonged periods, namely athletes (during the competitive season and off-season) and military personnel (during deployment). The primary purpose of this brief, narrative review is to identify the minimal dose of exercise (i.e., frequency, volume, and intensity) needed to maintain physical performance over time. In general populations, endurance performance can be maintained for up to 15 weeks when training frequency is reduced to as little as 2 sessions per week or when exercise volume is reduced by 33-66% (as low as 13-26 minutes per session), as long as exercise intensity (exercising heart rate) is maintained. Strength and muscle size (at least in younger populations) can be maintained for up to 32 weeks with as little as 1 session of strength training per week and 1 set per exercise, as long as exercise intensity (relative load) is maintained; whereas, in older populations, maintaining muscle size may require up to 2 sessions per week and 2-3 sets per exercise, while maintaining exercise intensity. Insufficient data exists to make specific recommendations for athletes or military personnel. Our primary conclusion is that exercise intensity seems to be the key variable for maintaining physical performance over time, despite relatively large reductions in exercise frequency and volume.

Impact of the COVID-19 Pandemic on Physical Activity and Sedentary Behaviour: A Qualitative Study in a Canadian City

Public health measures introduced to combat the COVID-19 pandemic have impacted the physical activity, health, and well-being of millions of people. This grounded theory study explored how the COVID-19 pandemic has affected physical activity and perceptions of health among adults in a Canadian city (Calgary). Twelve adults (50% females; 20-70 years) were interviewed between June and October (2020) via telephone or videoconferencing. Using a maximum variation strategy, participants with a range of sociodemographic characteristics, physical activity levels, and perceptions of seriousness and anxiety related to COVID-19 were selected. Semi-structured interviews captured participant perceptions of how their physical activity and perceptions of health changed during the pandemic. Using thematic analysis, four themes were identified: (1) Disruption to Daily Routines, (2) Changes in Physical Activity, (3) Balancing Health, and (4) Family Life. Participants experienced different degrees of disruption in their daily routines and physical activity based on their individual circumstances (e.g., pre-pandemic physical activity, family life, and access to resources). Although participants faced challenges in modifying their daily routines and physical activity, many adapted. Some participants reported enhanced feelings of well-being. Public health strategies that encourage physical activity and promote health should be supported as they are needed during pandemics, such as COVID-19.

Sports in time of COVID-19: Impact of the lockdown on team activity

The COVID-19 pandemic has affected many sectors of our global society since its detection in Wuhan in December 2019, and team sports have been no stranger to this reality. This special article presents a review of the literature exposing the dangers for athletes of this virus, reporting the effects of the pandemic on competitive sport, and making evidence-based recommendations to avoid the consequences of detraining in confined athletes. Furthermore, we present the results of a survey with 361 answers computed from coaches and different staff members from 26 different countries, representing the activity of more than 4500 athletes from all over the world. The aim was to know more teams’ activity during this cessation period. Finally, the article outlines recommendations based on the answers to help teams if a second outbreak of the virus forces massive confinements again, guiding a safe return to sport at any competitive level.

Effects of detraining on cardiorespiratory fitness of individuals with chronic stroke

BACKGROUND

Aerobic training can improve cardiorespiratory fitness in individuals after stroke. However, the effects of short-term and long-term detraining are not well known.

OBJECTIVE

To determine the effects of short-term (1-month) and long-term (6-month) detraining on cardiorespiratory fitness (VO_2peak) of individuals after stroke, who participated in aerobic training.

METHODS

A cohort study was developed. Twenty adults (57 ± 11 years old) with stroke were included. After completing an outpatient aerobic training, participants were divided into gain group (VO_2peak increase >1.3 ml.kg^-1.min^-1 from before to immediately after the training) or non-gain group (VO_2peak change ≤1.3 ml.kg^-1.min^-1). Cardiorespiratory fitness (VO_2peak), obtained by the cardiopulmonary exercise test was assessed one and 6 months after the end of the training (short- and long-term detraining, respectively), or collected retrospectively from patient chart (before and after the training).

RESULTS

There was found a significant interaction effect (time*group) for VO_2peak (F= 6.108;p < 0,001). Higher values in the VO_2peak observed in the gain group with the aerobic training (F = 25.86; p< .001) were significantly reduced with short-term detraining, reaching values similar to that observed before the training and to that of the non-gain group (F = 14.81;p= .001). Both groups had similar VO_2peak values within long-term detraining (F = 2.70;p= .12), with no significant differences from the values observed before the training and after short-term detraining (0.11 ≤ p≤ 1.00).

CONCLUSIONS

Detraining on cardiorespiratory fitness of individuals after chronic stroke occurred within only 1 month. Therefore, it is important to maintain aerobic training throughout life.

Effects of 12 months of detraining on health-related quality of life in patients receiving hemodialysis therapy

PURPOSE

Limited data exist regarding the effects of detraining on functional capacity and quality of life (QoL) in the hemodialysis population. The aim of the current study was to assess whether the discontinuation from a systematic intradialytic exercise training program will affect aspects of health-related QoL and functional capacity in hemodialysis patients.

METHODS

Seventeen hemodialysis patients (12 Males/5 Females, age 60.8 ± 13.6 year) participated in this study. Patients were assessed for functional capacity using various functional capacity tests while QoL, daily sleepiness, sleep quality, depression and fatigue were assessed using validated questionnaires at the end of a 12-month aerobic exercise program and after 12 months of detraining.

RESULTS

The detraining significantly reduced patients' QoL score by 20% (P = 0.01). More affected were aspects related to the physical component summary of the QoL (P < 0.001) rather than those related to the mental one (P = 0.096). In addition, the performance in the functional capacity tests was reduced (P < 0.05), while sleep quality (P = 0.020) and daily sleepiness scores (P = 0.006) were significantly worse after the detraining period. Depressive symptoms (P = 0.214) and the level of fatigue (P = 0.163) did not change significantly.

CONCLUSIONS

Detraining has a detrimental effect in patients' QoL, functional capacity and sleep quality. The affected physical health contributed significantly to the lower QoL score. It is crucial for the chronic disease patients, even during emergencies such as lockdowns and restrictions in activities to maintain a minimum level of activity to preserve some of the acquired benefits and maintain their health status.

A Longitudinal Prospective Study: The Effect of Annual Seasonal Transition and Coaching Influence on Aerobic Capacity and Body Composition in Division I Female Soccer Players

This study assessed how seasonal transitions and coaching influence affect aerobic capacity (AC) and body composition across the annual training cycle (ATC). Eleven division 1 female soccer players were tested after five predesignated time blocks (B1-B5): post-season 2016 (B1), nine-week transition (B2), spring season (B3), pre-season (B4), and post-season 2017 (B5). Height, weight, and body composition (fat-free mass (FFM)) were measured prior to a standardized 5 min treadmill running and dynamic movement warm up before a maximal AC test. Statistical analysis included a 4 × 5 repeated-measures analysis of variance (ANOVA) (dependent variable × time) with the Fishers Least Significant Difference (LSD) post-hoc test when relevant; data are presented as mean ± standard deviation, effect size (ES), and percent change (%). The statistical analysis revealed that the ATC had a significant main effect on AC and FFM (F_3,4 2.81, p = 0.001; η² = 0.22). There were significant increases in AC across the transition period (B1-B2) with reduced training volume (∆ + 12.9%, p = 0.001; ES = 0.50) while AC and FFM peaked after the spring season with directed concurrent training paired with adequate rest B1-B3 (∆ + 16.4%, p < 0.01; ES = 0.81). AC decreased across the pre-season with indirect training (B3-B4) (∆ - 7.0%, p = 0.02; ES = 0.50) and remained suppressed without change (p > 0.05) across the competitive season (B4-B5). Rest, concurrent training, and directed training positively affected AC, while indirect training and high training loads with little rest negatively affected AC.

Effects of exercise cessation on adipose tissue physiological markers related to fat regain: A systematic review

Tissues usually super compensate during the period that follow physical exercise. Although this is widely accepted for muscle and glycogen, the compensatory effect is not usually applied to fat tissues. Notwithstanding, evidence for this has been present since the 1970s when it was first suggested that the increased lipogenic activity in response to training might be an adaptation that enables to restore an energy reserve that can be used in times of need. In this context, the present review aimed to summarize information about the effect of detraining on fat metabolism and the physiological responses associated with fat regain. A systematic search on PubMed and Scielo was performed using "training cessation," "detraining," "exercise detraining," and "exercise cessation" combined with "fat tissue," "adipose tissue," "adipose metabolism," and "fat metabolism," as descriptors. From 377 results, 25 were included in this review, 12 humans and 13 rodents, resulting in a sample of 6772 humans and 613 animals. The analysis provided evidence for fat super compensation, as well as differences in humans and rodents, among different protocols and possible mechanisms for fat gain after exercise cessation. In summary, exercise cessation appears to increase the ability of the adipose tissue to store energy. However, caution should be taken, especially regarding conclusions based on investigations on humans, considering the multiple factors that could affect fat metabolism.

Variance in respiratory quotient among daily activities and its association with obesity status

BACKGROUND/OBJECTIVES

The ability to adapt the level of daily fuel utilization to substrate availability is given by the respiratory quotient (RQ), which its variance is an indicator of metabolic flexibility. Metabolic inflexibility is associated with many pathologies including obesity, but evidence relies on bed-rest studies and exercise-based interventions. Our goal was to examine the associations for RQ variance in response to daily living activities with obesity, in healthy adults.

SUBJECTS/METHODS

Participants (N = 50; 25 women), 20-64 years were lying for 60 min and randomly performed three conditions for 10 min each (sitting, standing, 1 sit/stand/sit transition min^-1). RQ was measured by indirect calorimetry and fat mass (FM), trunk FM (TFM), and fat-free mass (FFM) by DXA.

RESULTS

RQ variance among the three conditions was inversely associated with BMI (ß = 0.005; p < 0.001), FM (ß = 0.007; p = 0.024), and TFM (ß = 0.008; p = 0.026). A positive association was found between RQ variance and FFM (ß = -0.007; p = 0.024). No interactions for sex were found (p ≥ 0.05).

CONCLUSIONS

These findings suggest that a higher RQ variance in response to daily living metabolic challenges such as transitioning between sitting and standing is associated with lower overall and central obesity, as well as with a higher FFM, in healthy adults. Thus, RQ variance may work as an indication of metabolic flexibility, but these findings were obtained in a young and non-obese adult population without considering their fitness levels. Thus, further research in this field is warranted.

Repeated sprint in hypoxia as a time-metabolic efficient strategy to improve physical fitness of obese women

PURPOSE

To investigate the training and detraining effects of two different hypoxic high-intensity protocols on cardiorespiratory fitness, maximal fat oxidation and energy contribution in obese women.

METHODS

82 obese women completed a 12-week training of: (1) interval training in hypoxia (IHT; n = 19; 3 min at 90%W_max: 3 min at 55-65%W_max; FiO₂ = 17.2%), (2) interval training in normoxia (INT; n = 20; 3 min at 90%W_max: 3 min at 55-65%W_max), (3) repeated sprint training in hypoxia (RSH; n = 22; 30 s at 130%W_max: 3 min at 55-65%W_max; FiO₂ = 17.2%), and (4) repeated sprint training in normoxia (RSN; n = 21; 30 s at 130%W_max: 3 min at 55-65%W_max). VO_2max, workload, time to exhaustion and heart rate were assessed at baseline, after completion of 36 training sessions over 12 weeks and after 4 weeks of detraining.

RESULTS

Hypoxic training (IHT and RSH) showed a significant positive effect on absolute (p < 0.001) and relative maximal oxygen uptake (p < 0.001) as well as VT2 (%VO_2max; p < 0.001). Both IHT and RSH showed significantly higher values of absolute VO_2max (IHT: + 26.63%; RSH: + 19.79%) and relative VO_2max (IHT: + 27.95%; RSH: + 19.94%) between baseline and post-exercise (p < 0.001). VO_2max (IHT: + 21.74%; RSH: + 17.65%) and relative VO_2max (IHT: + 23.53%; RSH: + 17.15%) remained significantly higher after detraining in IHT and RSH (p < 0.001).

CONCLUSION

A larger improvement in cardiorespiratory fitness has been observed after high-intensity interval training under normobaric hypoxia. As interval training or repeated sprint training did not show a significant effect, RSH might provide a time-metabolic effective strategy in this population.

Differences in Training Adaptations of Endurance Performance during Combined Strength and Endurance Training in a 6-Month Crisis Management Operation

Decreases in aerobic fitness during military operations have been observed in several studies. Thus, differences in training adaptations during a 6-month crisis-management operation were compared by using the change in endurance performance as the outcome measure. Sixty-six male soldiers volunteered for the study, consisting of pre-post assessments of blood biomarkers, body composition, physical performance, and the military simulation test (MST) performance. Physical training volume was self-reported. After the follow-up, the data were divided based on individual changes in endurance performance. Endurance performance was improved in the high-responder group (HiR, n = 25) and maintained or decreased in the low-responder group (LoR n = 24). During the operation, the LoR group decreased while the HiR group increased their endurance training frequency from the pre-deployment level (Δ 28 ± 57% vs. -40 ± 62%, p = 0.004). Fat mass decreased (-7.6 ± 11.7% vs. 14.2 ± 20.4%, p < 0.001), and 1-min push-up (27.7 ± 21.9% vs. 11.7 ± 26.1%, p = 0.004) and MST performance improved (-13.6 ± 6.8% vs. -7.5 ± 6.5%, p = 0.006) more in the HiR group. No differences were observed in the changes of other physical performance test results or analyzed biomarkers. In conclusion, soldiers who were initially leaner and fitter in terms of lower body strength and power were more likely to decrease their aerobic fitness during the operation.

Maintenance motives for physical activity among older adults: a protocol for a systematic review and meta-analysis

INTRODUCTION

Physical activity (PA) is an important aspect for health and well-being, yet many older adults do not maintain their PA long term. The identification of key factors that are associated with, and likely causally related to, older adults' PA maintenance is a crucial first step towards developing programmes that are effective at promoting long-term PA behaviour change. The purpose of this protocol is to outline a systematic review that will examine the relationship between four motives (ie, satisfaction, enjoyment, self-determination and identity) and older adults' PA maintenance.

METHODS AND ANALYSIS

Studies that investigated PA maintenance with a sample mean age ≥55 years will be included. Five electronic databases (PubMed, Cumulative Index to Nursing and Allied Health Literature, SPORTDiscus, PsycINFO and ProQuest Dissertations and Theses) were searched on 6 April 2018 with no publication date limit (ie, from inception). One reviewer screened 100% of titles and abstracts (k=21 470) while a random subsample (20%) was screened independently by two reviewers. An update of the search was run on 1 October 2019. All studies for which the full text was retrieved will be independently screened by two reviewers. Data pertaining to study sample, design, motives, PA (eg, measurement validity evidence, study definition of maintenance) and essential bias domains (eg, bias due to missing data) will be extracted. Study-level effect sizes will be calculated, and if the number of studies is ≥5, a random-effects meta-analysis will be performed using inverse-variance methods; a narrative synthesis will be performed otherwise.

ETHICS AND DISSEMINATION

The university's Human Research Protection Program determined that the proposed study qualifies as exempt from the Institutional Review Board review under Exemption Category 4 (PROPEL #: 80047007). Results will be published in a peer-review journal, and the findings will help inform future interventions with older adults.

PROSPERO REGISTRATION NUMBER

CRD42018088161.

Cardiorespiratory fitness and muscular endurance responses immediately and 2 months after a whole-body Tabata or vigorous-intensity continuous training intervention

Young adults (52 females, 16 males; age = 21 ± 3 years; V̇O_2peak: 41 ± 6 mL/(kg·min)) were randomized into 3 groups: (i) no-exercise control (CTL; n = 15), (ii) Tabata (n = 27), or (iii) vigorous-intensity continuous training (VICT; n = 26) groups for a 4-week supervised training period (4 sessions/week). V̇O_2peak, time-to-fatigue (TTF), 5 km time-trial performance (TT), and muscular endurance were assessed at baseline, post-training (POST), and 2-month follow-up (FU). Response confidence intervals (CI) were used to classify individuals as likely responders (R; CI > 0). Both exercise interventions increased TTF and TT at POST (both p < 0.01), but these benefits were maintained at FU after VICT only (p < 0.01). Push-up performance was increased at POST and FU (both p < 0.01) after Tabata. VICT resulted in a greater proportion of TTF R versus both groups at POST (CTL: 1/15; VICT: 19/26; Tabata: 9/27) and versus Tabata at FU (3/15; 13/26; 4/27). VICT also had a greater proportion of TT R versus CTL at POST (2/15; 17/26; 10/27). Tabata had a greater proportion of R for maximum push-up repetitions versus both groups at POST (3/15; 6/26; 18/27) and versus CTL at FU (2/15; 10/26; 18/27). Collectively, VICT appears to be more effective for improving cardiorespiratory fitness, whereas whole-body Tabata confers larger improvements in push-up performance following short-term training. Novelty: Vigorous-intensity continuous training elicits larger improvements in cardiorespiratory fitness versus whole-body Tabata. Individual response profiles parallel group-level changes in cardiorespiratory fitness and muscular endurance.

Predicting Competition Performance in Short Trail Running Races with Lactate Thresholds

Trail running is a popular sport, yet factors related to performance are still not fully understood. Lactate thresholds have been thoroughly investigated in road running and correlate strongly with race performance, but to date few data are available about the value in trail running performance prediction. We examined 25 trail runners (age 31.2 ± 5.1 years, BMI 22.2 ± 1.82 kg/m²) with an initial graded exercise test for measurement of VO_2max (59.5 ± 5.2 ml.kg^‐1.min^{‐ 1}) and lactate thresholds (LT): LTAET (LT aerobic) 1.03 ± 0.59 mmol/l; 11.2 ± 1.1 km/h), IAT (individual lactate threshold) (2.53 ± 0.59 mmol/l; 15.4 ± 1.6 km/h) and LT4 (lactate threshold at 4 mmol/l) (16.2 ± 1.9 km/h). All runners subsequently participated in a 31.1 km XS trail race and 9 runners in a 21 km XXS trail race. Race performance times correlated negatively with the XS trail run (LTAET: r = ‐0.65, p < 0.01; LT4: r = ‐0.87, p < 0.01; IAT: r = ‐0.84, p < 0.01) and regression analysis showed that race performance could be predicted by: LT4: ‐324.15×LT4+13195.23 (R² = .753, F_1,23 = 70.02, p < 0.01). A subgroup analysis showed higher correlations with race performance for slower than faster runners. No correlations were found with the XXS race. Lactate thresholds can be of value in predicting trail race performance and help in designing training plans.

The Dose Response for Sprint Interval Training Interventions May Affect the Time Course of Aerobic Training Adaptations

Low vs. high volume sprint-interval training (SIT) sessions have shown similar physiological benefits after 8 weeks. However, the dose response and residual effects of shorter SIT bouts (<10 s) are unknown. Following a 6-wk control period, 13 healthy inactive males were assigned to a low dose (LDG: n = 7) or high dose (HDG: n = 6) supervised 6-wk intervention: ×2/wk of SIT (LDG = 2 sets of 5 × 6 s ON: 18 s OFF bouts; HDG = 4–6 sets); ×1/wk resistance training (3 exercises at 3 × 10 reps). Outcome measures were tested pre and post control (baseline (BL) 1 and 2), 72 h post (0POST), and 3-wk post (3POST) intervention. At 0POST, peak oxygen uptake (VO_2peak) increased in the LDG (+16%) and HDG (+11%) vs. BL 2, with no differences between groups (p = 0.381). At 3POST, VO_2peak was different between LDG (−11%) and HDG (+3%) vs. 0POST. Positive responses for the intervention’s perceived enjoyment (PE) and rate of perceived exertion (RPE) were found for both groups. Blood pressure, blood lipids, or body composition were not different between groups at any time point. Conclusion: LDG and HDG significantly improved VO_2peak at 0POST. However, findings at 3POST suggest compromised VO_2peak at 0POST in the HDG due to the delayed time course of adaptations. These findings should be considered when implementing high-dose SIT protocols for non-athletic populations.

Hypotensive Effect of Heated Water-Based Exercise Persists After 12-Week Cessation of Training in Patients With Resistant Hypertension

BACKGROUND

Heated water-based exercise (HEx) promotes a marked reduction of blood pressure (BP), but it is not entirely clear whether its effects on BP persist after cessation of HEx.

METHODS

We analyzed the effects of cessation of HEx on 24-hour ambulatory BP monitoring (ABPM) in patients with resistant hypertension (RH). Thirty-two patients (aged 53 ± 6 years) with RH (4 to 6 antihypertensive drugs) were randomly assigned to HEx (n = 16) or control (n = 16) groups. Antihypertensive therapy remained unchanged during the protocol. The HEx group participated in 36 sessions (60 minutes) in a heated pool (32^oC [89.6°F]) for 12 weeks (training), followed by 12 weeks of cessation of training. The control group was evaluated during the same period and instructed to maintain their habitual activities.

RESULTS

HEx and control groups had similar BP levels at baseline. HEx training reduced the 24-hour systolic (-19.5 ± 4.6 vs 3.0 ± 0.7 mm Hg, P = 0.001) and diastolic BP (-11.1 ± 2.4 vs 2.06 ± 0.9 mm Hg, P = 0.001) at week 12, compared with the control group. After 12 weeks of training cessation (week 24), 24-hour BP remained significantly lower in the HEx group than in the control group (-9.6 ± 3.8 vs 6.3 ± 3.5 mm Hg, P = 0.01 and -7.5±2.2 vs 2.2 ± 1.0 mm Hg, P = 0.009, for systolic and diastolic BP, respectively), although these differences were attenuated.

CONCLUSIONS

BP remained lower after cessation of 12-week training among patients with RH who underwent HEx compared with the controls. The carryover effects of HEx on BP may help to overcome the challenging problem of exercise compliance in long-term follow-up.

Preoperative Preparations for Enhanced Recovery After Surgery Programs: A Role for Prehabilitation

Preoperative risk assessment is valuable only if subsequent targeted optimization of patient care is allowed. Early assessment of high-risk surgical patients is essential to facilitate appropriate optimization. Preoperative assessment and optimization should not be exclusively focused on patients' comorbidities, but also include nutritional assessment, functional capacity, and promote healthy life style habits that affect surgical outcomes (eg, smoking cessation); it requires a multidisciplinary approach.

Concurrent Training Followed by Detraining: Does the Resistance Training Intensity Matter?

Sousa, AC, Marinho, DA, Gil, MH, Izquierdo, M, Rodríguez-Rosell, D, Neiva, HP, and Marques, MC. Concurrent training followed by detraining: does the resistance training intensity matter? J Strength Cond Res 32(3): 632-642, 2018-The aim of this study was to analyze the training and detraining (DT) effects of concurrent aerobic training and resistance training against 3 different external loads on strength and aerobic variables. Thirty-two men were randomly assigned to 4 groups: low-load (LLG, n = 9), moderate-load (MLG, n = 9), high-load (HLG, n = 8), and control group (CG, n = 6). Resistance training consisted of full squat (FS) with a low load (40-55% 1 repetition maximum [1RM]), a moderate load (55-70% 1RM), or a high load (70-85% 1RM) combined with jump and sprint exercises. Aerobic training was performed at 75% of the maximal aerobic speed for 15-20 minutes. The training period lasted for 8-week, followed by 4-week DT. Pretraining, post-training, and post-DT evaluations included 20-m running sprints (0-10 m: T10; 0-20 m: T20), shuttle run test, countermovement vertical jump (CMJ) test, and loading test (1RM) in FS. All the experimental groups showed improvements (p ≤ 0.05) in all the parameters assessed, except the LLG for T10 and the HLG for T20. The LLG, MLG, and HLG showed great changes in 1RM and V[Combining Dot Above]O2max compared with the CG (p ≤ 0.05), whereas the HLG and MLG showed a greater percentage change than the CG in T10 (p < 0.001) and CMJ (p ≤ 0.05). The 4-week DT period resulted in detrimental effects in all variables analyzed for all 3 experimental groups. In conclusion, our results suggest that strength training programs with low, moderate, or high external loads combined with low-intensity aerobic training could be effective for producing significant gains in strength and aerobic capacities. Moreover, the higher loads used increased gains in explosive efforts.

Oral Contraceptive Use Dampens Physiological Adaptations to Sprint Interval Training

PURPOSE

Oral contraceptive (OC) use reduces peak aerobic capacity (V˙O2peak); however, whether it also influences adaptations to training has yet to be determined. This study aimed to examine the influence of OC use on peak performance (peak power output [PPO]) and physiological adaptations (V˙O2peak and peak cardiac output [Q˙peak]) after sprint interval training (SIT) in recreationally active women.

METHODS

Women taking an OC (n = 25) or experiencing natural regular menstrual cycles (MC; n = 16) completed an incremental exercise test to assess V˙O2peak, PPO, and Q˙peak before, immediately after, and 4 wk after 12 sessions of SIT. The SIT consisted ten 1-min efforts at 100% to 120% PPO in a 1:2 work-rest ratio.

RESULTS

Though V˙O2peak increased in both groups after SIT (both P < 0.001), the MC group showed greater improvement (OC, +8.5%; MC, +13.0%; P = 0.010). Similarly, Q˙peak increased in both groups, with greater improvement in the MC group (OC, +4.0%; MC, +16.1%; P = 0.013). PPO increased in both groups (OC, +13.1%; MC, +13.8%; NS). All parameters decreased 4 wk after SIT cessation, but remained elevated from pretraining levels; the OC group showed more sustained training effects in V˙O2peak (OC, -4.0%; MC, -7.7%; P = 0.010).

CONCLUSION

SIT improved peak exercise responses in recreationally active women. However, OC use dampened V˙O2peak and Q˙peak adaptation. A follow-up period indicated that OC users had spared V˙O2peak adaptations, suggesting that OC use may influence the time course of physiological training adaptations. Therefore, OC use should be verified, controlled for, and considered when interpreting physiological adaptations to exercise training in women.

Heritability estimates of endurance-related phenotypes: A systematic review and meta-analysis

The aim of this study was to clarify heritability estimates for endurance-related phenotypes and the underlying factors affecting these estimates. A systematic literature search was conducted for studies reporting heritability estimates of endurance-related phenotypes using the PubMed database (up to 30 September 2016). Studies that estimated the heritability of maximal oxygen uptake (V˙O2max), submaximal endurance phenotypes, and endurance performance were selected. The weighted mean heritability for endurance-related phenotypes was calculated using a random-effects model. A total of 15 studies were selected via a systematic review. Meta-analysis revealed that the weighted means of the heritability of V˙O2max absolute values and those adjusted for body weight and for fat-free mass were 0.68 (95% CI: 0.59-0.77), 0.56 (95% CI: 0.47-0.65), and 0.44 (95% CI: 0.13-0.75), respectively. There was a significant difference in the weighted means of the heritability of V˙O2max across these different adjustment methods (P < .05). Moreover, there was evidence of statistical heterogeneity in the heritability estimates among studies. Meta-regression analysis revealed that sex could partially explain the heterogeneity in the V˙O2max heritability estimates adjusted by body weight. For submaximal endurance phenotypes and endurance performance, the weighted mean heritabilities were 0.49 (95% CI: 0.33-0.65) and 0.53 (95% CI: 0.27-0.78), respectively. There was statistically significant heterogeneity in the heritability estimates reported among the studies, and we could not identify the specific factors explaining the heterogeneity. Although existing studies indicate that genetic factors account for 44%-68% of the variability in endurance-related phenotypes, further studies are necessary to clarify these values.

Effects of maintaining different exercise intensities during detraining on aerobic capacity in Thoroughbreds

OBJECTIVE To determine whether racehorses undergoing regular exercise at 2 intensities or stall rest during a period of reduced training (detraining) would differentially maintain their cardiopulmonary and oxygen-transport capacities. ANIMALS 27 Thoroughbreds. PROCEDURES Horses trained on a treadmill for 18 weeks underwent a period of detraining for 12 weeks according to 1 of 3 protocols: cantering at 70% of maximal rate of oxygen consumption ([Formula: see text]o_2max) for 3 min/d for 5 d/wk (canter group); walking for 1 h/d for 5 d/wk (walk group); or stall rest (stall group). Standardized treadmill exercise protocols (during which cardiopulmonary and oxygen-transport variables were measured) were performed before and after detraining. RESULTS Mass-specific [Formula: see text]o_2max, maximal cardiac output, and maximal cardiac stroke volume of all groups decreased after 12 weeks of detraining with no differences among groups. After detraining, arterial-mixed-venous oxygen concentration difference did not decrease in any group, and maximal heart rate decreased in the walk and stall groups. Run time to exhaustion and speeds eliciting [Formula: see text]o_2max and maximal heart rate and at which plasma lactate concentration reached 4mM did not change in the canter group but decreased in the walk and stall groups. CONCLUSIONS AND CLINICAL RELEVANCE Horses following the cantering detraining protocol maintained higher values of several performance variables compared with horses following the walking or stall rest protocols. These results suggested that it may be possible to identify a minimal threshold exercise intensity or protocol during detraining that would promote maintenance of important performance-related variables and minimize reductions in oxygen-transport capacity in horses.

Dietary nitrate markedly improves voluntary running in mice

Nitrate supplementation is shown to increase submaximal force in human and mouse skeletal muscles. In this study, we test the hypothesis that the increased submaximal force induced by nitrate supplementation reduces the effort of submaximal voluntary running, resulting in increased running speed and distance. C57Bl/6N male mice were fed nitrate in the drinking water and housed with or without access to an in-cage running wheel. Nitrate supplementation in sedentary mice had no effect on endurance in a treadmill test, nor did it enhance mitochondrial function. However, after three weeks with in-cage running wheel, mice fed nitrate ran on average 20% faster and 30% further than controls (p<0.01). Compared to running controls, this resulted in ~13% improved endurance on a subsequent treadmill test (p<0.05) and increased mitochondrial oxidative capacity, as judged from a mean increase in citrate synthase activity of 14% (p<0.05). After six weeks with nitrate, the mice were running 58% longer distances per night. When nitrate supplementation was removed from the diet, the running distance and speed decreased to the control level, despite the improved endurance achieved during nitrate supplementation. In conclusion, low-frequency force improvement due to nitrate supplementation facilitates submaximal exercise such as voluntary running.

Hippocampal and Cerebral Blood Flow after Exercise Cessation in Master Athletes

While endurance exercise training improves cerebrovascular health and has neurotrophic effects within the hippocampus, the effects of stopping this exercise on the brain remain unclear. Our aim was to measure the effects of 10 days of detraining on resting cerebral blood flow (rCBF) in gray matter and the hippocampus in healthy and physically fit older adults. We hypothesized that rCBF would decrease in the hippocampus after a 10-day cessation of exercise training. Twelve master athletes, defined as older adults (age ≥ 50 years) with long-term endurance training histories (≥15 years), were recruited from local running clubs. After screening, eligible participants were asked to cease all training and vigorous physical activity for 10 consecutive days. Before and immediately after the exercise cessation period, rCBF was measured with perfusion-weighted MRI. A voxel-wise analysis was used in gray matter, and the hippocampus was selected a priori as a structurally defined region of interest (ROI), to detect rCBF changes over time. Resting CBF significantly decreased in eight gray matter brain regions. These regions included: (L) inferior temporal gyrus, fusiform gyrus, inferior parietal lobule, (R) cerebellar tonsil, lingual gyrus, precuneus, and bilateral cerebellum (FWE p < 0.05). Additionally, rCBF within the left and right hippocampus significantly decreased after 10 days of no exercise training. These findings suggest that the cerebrovascular system, including the regulation of resting hippocampal blood flow, is responsive to short-term decreases in exercise training among master athletes. Cessation of exercise training among physically fit individuals may provide a novel method to assess the effects of acute exercise and exercise training on brain function in older adults.

Effects of long-term training cessation in young top-level road cyclists

In cycling, it is common practice to have a break in the off season longer than 4 weeks while adopting an almost sedentary lifestyle, and such a break is considered to be long-term detraining. No previous studies have assessed the effect of training cessation with highly trained young cyclists. The purpose of the present investigation was to examine effects of 5 weeks of training cessation in 10 young (20.1 ± 1.4 years) male road cyclists for body composition, haematological and physiological parameters. After training cessation, body mass of cyclists increased (P = 0.014; ES = 0.9). [Formula: see text] (L · min^-1 = -8.8 ± 5.0%, mL · kg^-1·min^-1 = -10.8 ± 4.2%,), W_max (W = -6.5 ± 3.1%, W · kg^-1 = -8.5 ± 3.3%,), W_LT1 (W = -12.9 ± 7.0%, W · kg^-1 = -14.8 ± 7.4%,), W_LT2 (W = -11.5 ± 7.0%, W · kg^-1 = -13.4 ± 7.6%,) and haematological (red blood cells count, -6.6 ± 4.8%; haemoglobin, -5.4 ± 4.3% and haematocrit, -2.9 ± 3.0%) values decreased (P ≤ 0.028; ES ≥ 0.9). Five weeks of training cessation resulted in large decreases in physiological and haematological values in young top-level road cyclists suggesting the need for a shorter training stoppage. This long-term detraining is more pronounced when expressed relative to body mass emphasising the influence of such body mass on power output. A maintenance programme based on reduced training strategies should be implemented to avoid large declines in physiological values in young cyclists who aspire to become professionals.

Higher-Intensity Exercise Results in More Sustainable Improvements for VO2peak for Breast and Prostate Cancer Survivors

PURPOSE/OBJECTIVES

To examine peak volume of oxygen consumption (VO2peak) changes after a high- or low-intensity exercise intervention.

DESIGN

Experimental trial comparing two randomized intervention groups with control.

SETTING

An exercise clinic at a university in Australia.

SAMPLE

87 prostate cancer survivors (aged 47-80 years) and 72 breast cancer survivors (aged 34-76 years).

METHODS

Participants enrolled in an eight-week exercise intervention (n = 84) or control (n = 75) group. Intervention participants were randomized to low-intensity (n = 44, 60%-65% VO2peak, 50%-65% of one repetition maximum [1RM]) or high-intensity (n = 40, 75%-80% VO2peak, 65%-80% 1RM) exercise groups. Participants in the control group continued usual routines. All participants were assessed at weeks 1 and 10. The intervention groups were reassessed four months postintervention for sustainability.

MAIN RESEARCH VARIABLES

VO2peak and self-reported physical activity.

FINDINGS

Intervention groups improved VO2peak similarly (p = 0.083), and both more than controls (p < 0.001). The high-intensity group maintained VO2peak at follow-up, whereas the low-intensity group regressed (p = 0.021). The low-intensity group minimally changed from baseline to follow-up by 0.5 ml/kg per minute, whereas the high-intensity group significantly improved by 2.2 ml/kg per minute (p = 0.01). Intervention groups always reported similar physical activity levels.

CONCLUSIONS

Higher-intensity exercise provided more sustainable cardiorespiratory benefits than lower-intensity exercise.

IMPLICATIONS FOR NURSING

Survivors need guidance on exercise intensity, because a high volume of low-intensity exercise may not provide sustained health benefits.

Exercise deprivation increases negative mood in exercise-addicted subjects and modifies their biochemical markers

The aim of this study was to identify the possible association between biochemical markers of exercise addiction and affective parameters in a sample of athletes during 2weeks of withdrawal exercise. Eighteen male runners were distributed into a control group (n=10) composed of runners without exercise addiction symptoms and an exercise addiction group (n=8) composed of runners with exercise addiction symptoms. The volunteers performed a baseline evaluation that included affective questionnaires, blood samples, body composition and an aerobic test performed at ventilatory threshold I. After the baseline evaluation, the groups started an exercise withdrawal period that was sustained for 2weeks. During exercise withdrawal, an actigraph accelerometer was used to monitor the movement index, and CK and LDH were measured in blood samples to validate the non-exercise practice. At the end of the exercise withdrawal period, a blood collection, aerobic test and mood scale was performed in the re-test. The results showed that at the end of the experimental protocol, when compared with the control group, the exercise addiction group showed an increase in depression, confusion, anger, fatigue and decreased vigor mood that improved post-exercise, along with low levels of anandamide at all time-points evaluated and a modest increase in β-endorphin post-exercise. Moreover, the exercise addiction group showed a decrease in oxygen consumption and respiratory exchange ratio after the exercise withdrawal period, which characterized a detraining phenomenon. Our data suggest that a 2-week withdrawal exercise period resulted in an increase of negative mood in exercise addiction; additionally, exercise addiction showed low levels of anandamide.

EFFECTS OF PERIODIC AND CONTINUOUS RESISTANCE TRAINING ON MUSCLE STRENGTH IN DETRAINED WOMEN

It has been reported that periodic resistance training (retraining after short-term detraining) could maintain muscle performance. However, the training volume used in previous studies differed between continuous and periodic training groups. This study compared strength gains following 20 sessions of continuous and periodic resistance training programs. 60 healthy, detrained women were randomly assigned into one of two groups: (1) continuous resistance training group or (2) retraining resistance group. The continuous resistance training group performed a non-interrupted resistance training program for 10 wk., while the retraining resistance group trained for 5 wk., detrained 2 wk., and resumed training for 5 wk. All participants performed three sets of 8-12 maximum repetitions of lower- and upper-body exercises two days per week, with at least 48 hr. between sessions. There was no significant difference on knee extensors and elbow flexors peak torque gain between the continuous resistance training group and the retraining resistance group. The results suggest that 2 wk. of detraining does not affect strength gains after a total of 10 wk. in detrained women.

Prehabilitation to enhance perioperative care

Patients who are elderly, malnourished, anxious, and have a low physical function before surgery are likely to have suboptimal recovery from cancer surgery. A multimodal prehabilitation program is proposed, consisting of exercise training and nutritional and psychological support, which increases physiologic reserve before the stress of surgery. This interventional approach seems to improve ability to undergo the stress of surgery and faster recovery. The integration of exercise, adequate nutrition, and psychosocial components, with medical and pharmacologic optimization in the presurgical period, deserves to receive more attention by clinicians to elucidate the most effective interventions.

Post-Exercise Protein Trial: Interactions between Diet and Exercise (PEPTIDE): study protocol for randomized controlled trial

BACKGROUND

Performing regular exercise is known to manifest a number of health benefits that mainly relate to cardiovascular and muscular adaptations to allow for greater oxygen extraction and utilization. There is increasing evidence that nutrient intake can affect the adaptive response to a single exercise bout, and that protein feeding is important to facilitate this process. Thus, the exercise-nutrient interaction may potentially lead to a greater response to training. The role of post-exercise protein ingestion in enhancing the effects of running-based endurance exercise training relative to energy-matched carbohydrate intervention remains to be established. Additionally, the influence of immediate versus overnight protein ingestion in mediating these training effects is currently unknown. The current protocol aims to establish whether post-exercise nutrient intake and timing would influence the magnitude of improvements during a prescribed endurance training program.

METHODS/DESIGN

The project involves two phases with each involving two treatment arms applied in a randomized investigator-participant double-blind parallel group design. For each treatment, participants will be required to undergo six weeks of running-based endurance training. Immediately post-exercise, participants will be prescribed solutions providing 0.4 grams per kilogram of body mass (g · kg(-1)) of whey protein hydrolysate plus 0.4 g · kg(-1) sucrose, relative to an isocaloric sucrose control (0.8 g · kg(-1); Phase I). In Phase II, identical protein supplements will be provided (0.4 + 0.4 g · kg(-1) · h(-1) of whey protein hydrolysate and sucrose, respectively), with the timing of ingestion manipulated to compare immediate versus overnight recovery feedings. Anthropometric, expired gas, venous blood and muscle biopsy samples will be obtained at baseline and following the six-week training period.

DISCUSSION

By investigating the role of nutrition in enhancing the effects of endurance exercise training, we will provide novel insight regarding nutrient-exercise interactions and the potential to help and develop effective methods to maximize health or performance outcomes in response to regular exercise.

TRIAL REGISTRATION

Current Controlled Trials registration number: ISRCTN27312291 (date assigned: 4 December 2013). The first participant was randomized on 11 December 2013.

Mechanisms modulating skeletal muscle phenotype

Mammalian skeletal muscles are composed of a variety of highly specialized fibers whose selective recruitment allows muscles to fulfill their diverse functional tasks. In addition, skeletal muscle fibers can change their structural and functional properties to perform new tasks or respond to new conditions. The adaptive changes of muscle fibers can occur in response to variations in the pattern of neural stimulation, loading conditions, availability of substrates, and hormonal signals. The new conditions can be detected by multiple sensors, from membrane receptors for hormones and cytokines, to metabolic sensors, which detect high-energy phosphate concentration, oxygen and oxygen free radicals, to calcium binding proteins, which sense variations in intracellular calcium induced by nerve activity, to load sensors located in the sarcomeric and sarcolemmal cytoskeleton. These sensors trigger cascades of signaling pathways which may ultimately lead to changes in fiber size and fiber type. Changes in fiber size reflect an imbalance in protein turnover with either protein accumulation, leading to muscle hypertrophy, or protein loss, with consequent muscle atrophy. Changes in fiber type reflect a reprogramming of gene transcription leading to a remodeling of fiber contractile properties (slow-fast transitions) or metabolic profile (glycolytic-oxidative transitions). While myonuclei are in postmitotic state, satellite cells represent a reserve of new nuclei and can be involved in the adaptive response.