Effects Of Detraining Research Articles

Effects of detraining on cardiorespiratory fitness of individuals with chronic stroke

ABSTRACT 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 (VO2peak) 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 (VO2peak increase >1.3 ml.kg−1.min−1 from before to immediately after the training) or non-gain group (VO2peak change ≤1.3 ml.kg−1.min−1). Cardiorespiratory fitness (VO2peak), 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 VO2peak (F= 6.108;p < 0,001). Higher values in the VO2peak 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 VO2peak 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.

Wearable resistance sprint running is superior to training with no load for retaining performance in pre-season training for rugby athletes

This study determined the effects of a six-week lower-limb wearable resistance training (WRT) intervention on sprint running time, velocity, and horizontal force-velocity mechanical variables. Twenty-two collegiate/semi-professional rugby athletes completed pre- and post-intervention testing of three maximal effort 30 m sprints. A radar device was used to measure sprint running velocity from which horizontal force-velocity mechanical profiling variables were calculated. All athletes completed two dedicated sprint training sessions a week for six-weeks during pre-season. The intervention (wearable resistance, WR) group completed the sessions with 1% body mass load attached to the left and right shanks (i.e. 0.50% body mass load on each limb), whilst the control group completed the same sessions unloaded. For the control group, all variables were found to detrain significantly (p ≤ 0.05) over the training period with large detraining effects (ES > 0.80) for theoretical maximal horizontal force, slope of the force-velocity profile, maximal ratio of force, index of force application, 5 and 10 m times. For the WR group, there were no significant changes to any recorded variables (all p > 0.05) and all effects of training were trivial or small (ES < 0.50). After adjustment for baseline differences, significant between group differences were found for all variables (large effects, ES > 0.80) except theoretical maximal velocity, 30 m time, and maximal velocity. The addition of light wearable resistance to sprint training during a six-week pre-season block enables the maintenance of sprint performance and mechanical output qualities that otherwise would detrain due to inadequate training frequencies.

How to Improve the Functional Capacity of Frail and Pre-Frail Elderly People? Health, Nutritional Status and Exercise Intervention. The EXERNET-Elder 3.0 Project

Aging is associated with the impairment of health and functional capacity, and physical exercise seems to be an effective tool in frailty prevention and treatment. The purpose of this study was to present the methodology used in the EXERNET-Elder 3.0 project that aims to evaluate the immediate and residual effects and of a multicomponent exercise training program called Elder-fit on frailty, fitness, body composition and quality of life, and also to analyse a possible dietary intake interaction according to health and metabolic status. A total of 110 frail and pre-frail elders participated in this study and were divided into a control group (CG = 52) and an intervention group (IG = 58). The IG performed a supervised multicomponent exercise training program of 6 months and 3 days per week, which included strength, endurance, balance, coordination and flexibility exercises, while the CG continued with their usual daily activities. Both groups received four speeches about healthy habits along the project. Four evaluations were performed: at baseline, after 3 months of training, at the end of the training program (6 months) and 4 months after the program had ended to examine the effects of detraining. Evaluating the efficacy, safety and feasibility of this program will help to develop efficacious physical interventions against frailty. Further, protocols should be described accurately to allow exercise programs to be successfully replicated.

Reducing impulsive choice VII: effects of duration of delay-exposure training.

Impulsive choice is related to substance use disorders, obesity, and other behaviors that negatively impact human health. Reducing impulsive choice may prove beneficial in ameliorating these maladaptive behaviors. Preclinical research in rats indicates that one reliable method for producing large and lasting reductions in impulsive choice is delay-exposure (DE) training. In all six of the prior DE-training experiments, rats were given extensive experience (~ 120 training sessions) with a delayed reinforcement contingency. The present experiment evaluated if similar large and lasting reductions in impulsive choice could be achieved with less training. The duration of DE training between groups of male Wistar rats was 0 sessions (training ended after a lever-pressing acquisition criterion was met), 30, 60, or 120 sessions. Comparison groups were given the same durations of training with immediate reinforcement. A post-training assessment of impulsive choice was completed using an increasing-delay procedure. For rats assigned to the 60-session condition, impulsive choice was reassessed at a 120-day follow-up. DE training reduced impulsive choice but, contrary to expectation, reductions in impulsive choice did not increase with DE-training duration (no significant training-duration by group interaction). Importantly, 60 sessions of DE training produced reductions in impulsive choice that were comparable to prior published findings and this effect remained significant at the 120-day follow-up. Procedural elements that may be responsible for the DE-training effect, and how they could be improved in future experiments, are discussed.

Strength Adaptions And Body Composition Changes Following High Vs. Low Volume Resistance Training And Detraining

Resistance training (RT) is used for improving strength and body composition. However, it is still under debate whether higher RT volume (HV) is necessary in novices, or if lower volume (LV) is equally effective. In addition, effects of detraining (DTR) following HV and LV RT are not well understood. PURPOSE: To determine the effects of a 12-week HV program (3 sets, 10 repetitions) compared to LV RT (1 set, 10 repetitions) to concentric muscle failure on strength and body composition, followed by four weeks of DTR in male and female subjects. METHODS: Forty-two untrained subjects were randomly assigned to either LV (female n=10; male n=10; age 32.9±11.8y, height 174.2±8.4cm; weight 70.3±13.5kg) or HV RT (female n=11; male n=11; age 33.0±9.6y, height 174.2±11.2cm; weight 72.4±18.1 kg). RT consisted of two RT sessions per week (squat, bench press, arm and leg flexion and extension). Measurements were taken prior to and post RT, and after DTR. Body composition was assessed using BIA. Strength measurement (10-RM) was done using the aforementioned exercises. Six subjects were eliminated from the study due to various reasons, resulting in 36 subjects included for further analysis (HV female n=10, male n=8; LV female n=9, male n=9). Compliance was 100%. Comparisons were made using two-way ANOVA with repeated measures. RESULTS: Both groups increased strength through RT with no difference between groups (squat HV 61.1% vs. LV 59.0%, p<0.001; bench press HV 28.9% vs. LV 31.3%, p<0.001; leg extension HV 54.6% vs. LV 50.2%, p<0.001; leg flexion HV 30.9% vs. LV 30.3%, p<0.001; arm extension HV 51.0% vs. LV 44.8%, p<0.001; arm flexion HV 36.9% vs. LV 31.7%, p<0.001). Body mass (p=0.182), fat mass (p=0.238), and fat-free mass (p=1.000) was unaltered by RT. After DTR strength in arm flexion (p=0.007), arm extension (p=0.001), bench press (p<0.001), and squat (p=0.039) decreased to the same extend in both groups. Leg flexion and extension strength was unaltered following DTR, while fat-free mass increased (p=0.004). CONCLUSION: HV and LV RT was equally effective in untrained subjects to increase strength. Novices could therefore save time with LV, with similar results. Yet, RT alone was not sufficient to change body composition. Following DTR strength gains were still elevated but in some measurements slightly lower than post RT.

63Effects of exercise-based cardiac rehabilitation and detraining on exercise capacity and cardiac function in patients with atrial fibrillation: a randomized controlled trial with 1-year follow-up

Abstract Introduction We aimed to determine whether maximal exercise capacity, left ventricular function, and quality of life (QoL) scores are sustained in patients with atrial fibrillation (AF) after termination of training following exercise-based cardiac rehabilitation (ECR). Methods In a prospective study, 58 patients with AF (age, 62 ± 7 years) were randomized into an exercise training group for 12 months (ECR, n = 13), a group with 6-month detraining after a 6-month exercise training (DT, n = 15), and a medical treatment only group (MT, n = 30). For exercise training, cycling on a bicycle ergometer was performed in the DT and ECR groups 3 times a week for 6 and 12 months, respectively. Each session started with a 10-minute warm-up at 60%–70% of the maximal heart rate (HRpeak), followed by four 4-minute intervals at 80%–90% of the HRpeak, with 3 minutes of active recovery at 60%–70% of the HRpeak between intervals, ending with a 5-minute cool-down period. Peak exercise oxygen consumption (Vo2), left ventricular function, plasma lipid level, N-terminal pro B-type natriuretic peptide level, and QoL score were measured at baseline, after 6 months of training, and after additional 6 months of continuous training or detraining follow-up assessments. Results Six months of exercise training increased the peak Vo2 (ECR: 28.2 ± 7.0 ml/[kg·min] and DT: 28.0 ± 8.3 ml/[kg·min] vs. MT: 23.0 ± 5.2 ml/[kg·min], p= 0.047) and QoL scores (36-Item Short-form Health Survey) and decreased the total cholesterol level (ECR: 146.8 ± 43.8 mg/dl and DT: 140.6 ± 22.4 vs. MT: 182 ± 44.2 mg/dl, p = 0.008). Detraining resulted in an increase in QoL score and a decrease in total cholesterol level (ECR: 142.8 ± 21.4 mg/dl and DT: 151.8 ± 39.8 vs. MT: 176.8 ± 34.2 mg/dl, p = 0.017). However, the exercise training-induced increase in peak Vo2 reverted to the baseline level after detraining (ECR: 27.1 ± 5.1 ml/kg/min vs. DT: 24.4 ± 7.2 ml/[kg·min] and MT: 21.5 ± 4.86 ml/[kg·min], p = 0.017). The resting left ventricular systolic and diastolic functions were not significantly different, with no inter-group difference after 6 months of training and 6 months of continuous training or detraining. Conclusions As the QoL scores are maintained despite peak Vo2 being lowered by detraining after an exercise training period in patients with AF, physicians should encourage patients’ participation in a continuous exercise program to sustain the improvement in both the QoL score and peak Vo2 with exercise training. Further studies with larger sample sizes are needed to observe the long-term effects of exercise training and detraining.

Detraining attenuation during the COVID-19 pandemic: practical considerations for home-based strength and power training

The COVID-19 pandemic that scattered across the world in 2020 has required collective action to control the transmission of the disease. Among the measures, social distancing has been widely adopted, aiming to reduce contact and people gathering. With the limited access to training places that have equipment and a variety of loads for strength and power training, alternative strategies to be carried out in the domestic environment are important for maintaining physical conditioning and mitigating the deleterious effects of detraining. Based on the available scientific literature, this article presents practical recommendations for strength training in the home environment. It is recommended to perform exercises that employ self-body weight, household items and, when available, dumbbells and elastic bands. Whenever using low loads (30-50% of 1 repetition maximum), performing the sets until the concentric failure seems to be necessary to optimize gains in strength and muscle mass. The practice of physical exercises should be performed on most days of the week (&gt; 5 days/week), combined with domestic and leisure activities that involve the movement of the whole body. For maintenance and / or development of muscle power, ballistic movements must be included, in the presence or absence of external loads.Keywords: strength training, power, detraining, COVID-19.

The Effect of Proprioceptive Training on Directional Dynamic Stabilization.

Significant loss of playing time and the impact of treatment costs due to lower limb injury in football demonstrates a need for improved protocols for injury risk reduction. The aim of the present study is to assess the effect of a proprioceptive training program on the lower limb dynamic stability of elite footballers. A total of 16 elite premier league footballers were randomly allocated by matched pair design to a 8-week proprioception training group (group A, n = 8) or nontraining group (group B, n = 8), to determine the effect of this training over a 16-week period. Group A completed 8 weeks of bilateral proprioceptive training, 5 times per week for 10minutes. The Biodex Stability System measures of overall stability index, anterior-posterior (A-P), and medial-lateral stability (M-L) at levels 8-6-4-1 were taken for both groups at baseline, 4, 8, and 16 weeks. Main effects of time, level of stability, and direction of stability were determined, with comparisons of effect made between the 2 groups. The training group displayed significant differences for multidirectional stability at week 8 (P ≤ .05). The A-P stability within the training group displayed significant differences between baseline measures and 16 weeks (P > .05), with significant increases in scores displayed for M-L and A-P stability between weeks 8 and 16 (P ≤ .05), representing a detraining effect. No significant differences were detected at any time point for the nontraining group (P > .05). Proprioceptive training over 8 weeks has a positive effect on all directions of stability. Greater declines in A-P stability were evident at 16 weeks when compared with M-L and overall stability index. Consideration must be given to the increased stability scores presented pretesting for A-P when compared with M-L. Findings of this work present implications for training design.

운동중지가 난소절제 쥐의 골밀도, 골대사 지표 및 골수세포의 OPG, RANKL mRNA 발현에 미치는 영향

The aim of this study was to evaluate the effects of exercise detraining on bone mineral density (BMD), bone metabolism marker and OPG, RANKL mRNA expression of bone marrow cell in ovariectomized rats. Female Sprague-Dawley rats were divided into OVX (ovariectomy, n=10), OVX-EXE (ovariectomy-combined exercise, n=10), and OVX-EC (exercise cessation after combined exercise, n=10). Combined exercise training was performed on a treadmill and ladder adapted to rats in alternate days (4 days/wk, for 12 wk). This was followed by 8 week of exercise detraining. Compared to the OVX group, exercise intervention increased BMD and bone breaking force (p<0.05). It is also serum bone metabolic-related factors (CTx-1, IL-1β, IL-6) and OPG mRNA were significant difference (p<0.05). After the exercise detraining period, all variable in the OVX-EXE groups were still greater than in the OVX groups. These results suggest that regular exercise is an effective therapeutic strategy to prevent and delay postmenopausal osteoporosis and its effectiveness is still preserved after exercise detraining.

Does the combination of photobiomodulation therapy (PBMT) and static magnetic fields (sMF) potentiate the effects of aerobic endurance training and decrease the loss of performance during detraining? A randomised, triple-blinded,\xa0placebo-controlled trial

BackgroundPhotobiomodulation (PBMT) is a therapy that uses non-ionising forms of light, including low-level lasers and light-emitting diodes (LEDs) that may be capable of modulating cellular activity. Some biological processes may also interact with static magnetic fields (sMF), leading to modulatory effects on cells. Previous studies have verified that the combination of PBMT and sMF (PBMT/sMF) enhances the performance of individuals during aerobic training programs. The detraining period can cause losses in aerobic capacity. However, there is no evidence of the existence of any recourse that can decrease the effects of detraining. We aimed to investigate the effects of PBMT/sMF application during training and detraining to assess the effectiveness of this treatment in reducing the effects of detraining.MethodsSixty male volunteers were randomly allocated into four groups— participants who received PBMT/sMF during the training and detraining (PBMT/sMF + PBMT/sMF); participants who received PBMT/sMF during the training and a placebo in the detraining (PBMT/sMF + Placebo); participants who received a placebo during the training and PBMT/sMF in the detraining (Placebo+PBMT/sMF); and participants who received a placebo during the training and detraining (Placebo+Placebo). Participants performed treadmill training over 12 weeks (3 sessions/week), followed by 4 weeks of detraining. PBMT/sMF was applied using a 12-diode emitter (four 905 nm super-pulsed lasers, four 875 nm light-emitting diodes (LEDs), four 640 nm LEDs, and a 35 mT magnetic field) at 17 sites on each lower limb (dosage: 30 J per site). The data were analysed by two-way repeated measures analysis of variance (ANOVA, time vs experimental group) with post-hoc Bonferroni correction.ResultsThe percentage of change in time until exhaustion and in maximum oxygen consumption was higher in the PBMT/sMF + PBMT/sMF group than in the Placebo+Placebo group at all time-points (p < 0.05). Moreover, the percentage of decrease in body fat at the 16th week was higher in the PBMT/sMF + PBMT/sMF group than in the Placebo+Placebo group (p < 0.05).ConclusionsPBMT/sMF can potentiate the effects of aerobic endurance training and decrease performance loss after a 4-week detraining period. Thus, it may prove to be an important tool for both amateur and high-performance athletes as well as people undergoing rehabilitation.Trial registrationNCT03879226. Trial registered on 18 March 2019.

The effects of short-term moderate intensity aerobic exercise and long-term detraining on electrocardiogram indices and cardiac biomarkers in postmenopausal women

ObjectiveThe purpose of this study was to investigate the effects of 12-week of moderate-intensity aerobic exercise and 5-month detraining on electrocardiogram (ECG) indices and serum levels of 25-hydroxivitamin D (Vit D), parathyroid hormone (PTH), calcium (Ca2+), and phosphorus (P) in postmenopausal women (PMWs). Materials and methodsThirty-one PMWs (aged 50–70 yrs) were randomized to exercise (EX, n = 16) and control (C, n = 15) groups. EX group performed of 12-week of warm up- walking/jogging moderate intensity aerobic exercise training program- recovery (60 min/day, 3 days/week at 70% of maximal heart rate reserve), and then 5-month detraining remained. C group maintain their normal lifestyle during 8 months. The ECG indices and cardiac serum levels were measured at baseline, after 12-week exercise, and after 5-month detraining. ResultsAfter 12-week exercise intervention, P-R interval, serum PTH and serum Vit D were significantly increased in the EX group compared to the C group (P = 0.020, P = 0.001 and P = 0.001, respectively). After 5-month detraining, P-R segment and S-T interval were significantly decreased (P = 0.042 and P = 0.001, respectively) while serum Vit D was significantly increased (P = 0.014) in the EX group compared to the C group. ConclusionsThe results suggested that 12-week of moderate intensity aerobic exercise increased the P-R interval, PTH and Vit D, as severe Vit D deficiency status (below 10 ng/ml) improved to Vit D deficiency status (between 10 and 20 ng/ml) in PMWs. Also, long-term positive adaptations to aerobic exercise such as increased Vit D were observed even after 5-month detraining. In addition, P-R segment and S-T interval decreased after 5-month detraining in sedentary PMWs, which may be a sign of atrial positive adaptations to aerobic exercise.

Effects of exercise training and detraining on atheromatous matrix metalloproteinase activity in mice

Background and aimsExercise training (ET) helps treat atherosclerosis. However, many patients stop regular ET for various reasons. The effect of detraining on atherosclerosis is not well studied. We examined the effects of ET vs. short-term detraining on atheromatous matrix-metalloproteinase (MMP) activity in preexisting plaque and circulating cytokines/lipids. Methods and resultsEighteen-week-old apolipoprotein-E−/− mice (n = 56) on a Western diet underwent: 1) ET for 6-weeks (ET5+1), 2) ET for 5-weeks and detraining for 1-week (ET5+0), 3) ET for the last 1-week (ET0+1), or 4) no treadmill ET at all for 6-weeks (ET0+0). Atheromatous MMP-activity was visualized using molecular imaging with an MMP-2/9-activatable near-infrared-fluorescent probe. Compared with no ET (ET0+0), regular ET (ET5+1) decreased carotid atheromatous MMP activity, but this protective effect was significantly blunted by short-term detraining (ET5+0). Short-term detraining after longer-term ET showed a reduction in MMP-activity similar to short-term ET (ET0+1). Blood levels of lipids and cytokines paralleled the molecular imaging results: exercise caused higher levels of high-density lipoprotein, adiponectin, and interleukin-10 and lower levels of vascular cell adhesion molecule, monocyte chemoattractant protein-1, interleukin-1β, and low-density lipoprotein. However, this beneficial effect was short-lived, with the ET5+0 group being similar to the ET0+0 group, and the ET0+1 group being similar to the ET5+1 group. The effect of exercise can be modeled with an exponential-decay of the protective factor of about 15%/day. ConclusionsEven short-term detraining reduces atheroprotective effects, and tips the balance towards atherosclerosis. This suggests that ET, to be effective, needs to be prolonged and regular, and that detraining should be avoided.

Effects of high vs moderate-intensity intermittent training on functionality, resting heart rate and blood pressure of elderly women

BackgroundThe present study compared the effects of training and detraining periods of high-intensity interval training (HIIT), moderate-intensity interval training (MIIT) and moderate-intensity continuous training (MICT) on functional performance, body composition, resting blood pressure and heart rate in elderly women nursing home residents.MethodsForty-six volunteers (age, 80.8 ± 5.2 y; body mass, 69.8 ± 5.2 kg, height, 164.2 ± 4.12 cm) were divided into groups that performed treadmill exercise twice-weekly HIIT (4 bouts of 4-min intervals at 85–95% of the maximal heart rate [HRmax], interspersed by 4 min at 65% HRmax), MIIT (4 bouts of 4 min intervals at 55–75% HRmax, interspersed by 4 min at 45–50% HRmax) and MICT (30-min at 55–75% HRmax). Tests were performed before and after 8 weeks of training and 2 and 4 weeks of detraining. ANCOVA was used to analyze dependent variable changes.ResultsAfter 8 weeks HIIT promoted greater reductions in body mass (HIIT = − 1.6 ± 0.1 kg; MICT = − 0.9 ± 0.1 kg; MIIT = − 0.9 ± 0.1 kg; p = 0.001), fat mass (HIIT = − 2.2 ± 0.1%; MICT = − 0.7 ± 0.1%; MIIT = − 1.2 ± 0.1%; p < 0.001) and resting heart rate (HIIT = − 7.3 ± 0.3%; MICT = − 3.6 ± 0.3%; MIIT = − 5.1 ± 0.3%; p < 0.001) and greater improvement in the chair stand test (HIIT = 3.4 ± 0.1 reps; MICT = 2.5 ± 0.1 reps; MIIT = 3.1 ± 0.1 reps; p < 0.001) when compared to MIIT and MICT. These improvements were sustained after 2 and 4 weeks of detraining only in the HIIT group.ConclusionHIIT promoted greater benefits for body composition and functional performance than MICT and MIIT and also showed less pronounced effects of detraining. This suggests that the intensity of physical exercise is an important factor to consider when prescribing exercise to the elderly.

Tongue-Strengthening Exercises in Healthy Older Adults: Effect of Exercise Frequency – A Randomized Trial

Introduction: Positive effects from tongue-strengthening exercises (TSE) are widely described, but dose-dependent studies concerning exercise frequency have not yet been reported. This study aimed to determine the training and detraining effects of TSE with exercise frequencies of respectively 3 and 5 times per week on maximum isometric anterior and posterior tongue pressures (MIP_A and MIP_P) and on anterior and posterior tongue strength during an effortful saliva swallow (Pswal_A and Pswal_P). Method: Twenty healthy adults were randomly assigned to two exercise groups, training 3 (EX3, n = 10) or 5 (EX5, n = 10) times per week with the Iowa Oral Performance Instrument. MIP_A, MIP_P, Pswal_A, and Pswal_P were measured at baseline, after 4 and 8 weeks of training and 4 and 8 weeks after the last training session to document detraining effects. Descriptive statistics, linear mixed model effects, and post hoc analyses were calculated. Results: Significant increases in MIP_A, MIP_P, Pswal_A, and Pswal_P were measured for training both 3 and 5 times per week. No significant differences on any parameter were found between EX3 and EX5 groups. No significant detraining effects were found after 4 or 8 weeks in any treatment arm either for MIPs or for effortful swallow pressures. Conclusion: This randomized study demonstrated a positive effect of TSE on MIP and Pswal in healthy older adults, without detraining effects. No superiority of exercise frequency was identified based on significance testing, although some trends are discussed.

The effect of resistance training, detraining and retraining on muscle strength and power, myofibre size, satellite cells and myonuclei in older men.

Ageing is associated with an attenuated hypertrophic response to resistance training and periods of training interruptions. Hence, elderly would benefit from the 'muscle memory' effects of resistance training on muscle strength and mass during detraining and retraining. As the underlying mechanisms are not yet clear, this study investigated the role of myonuclei during training, detraining and retraining by using PCM1 labelling in muscle cross-sections of six older men. Knee extension strength and power were measured in 30 older men and 10 controls before and after 12 weeks resistance training and after detraining and retraining of similar length. In a subset, muscle biopsies from the vastus lateralis were taken for analysis of fibre size, fibre type distribution, Pax7+ satellite cell number and myonuclear domain size. Resistance training increased knee extension strength and power parameters (+10 to +36%, p<.001) and decreased the frequency of type IIax fibres by half (from 20 to 10%, p=.034). Detraining resulted in a modest loss of strength and power (-5 to -15%, p≤.004) and a trend towards a fibre-type specific decrease in type II fibre cross-sectional area (-17%, p=.087), type II satellite cell number (-30%, p=.054) and type II myonuclear number (-12%, p=.084). Less than eight weeks of retraining were needed to reach the post-training level of one-repetition maximum strength. Twelve weeks of retraining were associated with type II fibre hypertrophy (+29%, p=.050), which also promoted an increase in the number of satellite cells (+72%, p=.036) and myonuclei (+13%, p=.048) in type II fibres. Changes in the type II fibre cross-sectional area were positively correlated with changes in the myonuclear number (Pearson's r between 0.40 and 0.73), resulting in a stable myonuclear domain. Gained strength and power and fibre type changes were partially preserved following 12 weeks of detraining, allowing for a fast recovery of the 1RM performance following retraining. Myonuclear number tended to follow individual changes in type II fibre size, which is in support of the myonuclear domain theory.

Effect of Exergame Training and Detraining on Lower-Body Strength, Agility, and Cardiorespiratory Fitness in Women with Fibromyalgia: Single-Blinded Randomized Controlled Trial.

The aim of this study was to analyze the effects of a 24 week exergame intervention and 24 weeks of detraining on lower-limb strength, agility, and cardiorespiratory fitness in women with fibromyalgia (FM). It was performed as a single-blinded randomized controlled trial of 55 women with FM. University facilities were used. The 24 week exergame intervention was focused on mobility, postural control, upper- and lower-limb coordination, aerobic fitness, and strength. Participants performed 120 min of exergaming per week, which was divided into two sessions. Twenty-four weeks after the end of the intervention, participants were re-evaluated. A chair–stand test, 10 step stair test, and six-minute walk test were conducted to assess lower-body strength, agility, and cardiorespiratory fitness, respectively. The exergame intervention significantly improved lower-limb strength and cardiorespiratory fitness. However, no significant effects on agility were observed. After the detraining period, lower-limb strength and agility returned to their baseline level, but improvements in cardiorespiratory fitness were sustained over time. Exergaming was therefore shown to be beneficial for physical fitness in people with FM. However, exergames had to be played regularly to maintain the benefits. This long-term intervention (24 weeks) may have changed the lifestyle of women with FM, which could explain why cardiorespiratory fitness improvements remained after the detraining period. Future research should focus on lifestyle changes after long-term interventions.

Improvement in Muscular Strength in HIV-Infected Individuals Receiving Antiretroviral Therapy.

Purpose: This study investigated (1) the effect of a progressive resistance training (PRT) program and whey protein intake on maximal muscle strength in human immunodeficiency virus (HIV)-infected individuals receiving antiretroviral therapy (ART) and (2) alterations in maximal strength 12 wks after the cessation of PRT with continued supplementation. Methods: Sixty HIV-infected individuals were recruited. Whole body PRT was performed twice weekly for 12 wks. Participants received, in a double-blind placebo controlled manner, either 20 g whey or placebo (maltodextrin) before and immediately after each session. Both PRT groups continued to take either whey protein or placebo for a further 12 wks following the exercise intervention to examine the effects of detraining. Results: Forty participants (mean and standard deviation (SD) age 40.8 (±7.7) years, weight 70.8 (±16) kg, body mass index (BMI) 30.9 (±7.2) kg m2); whey protein /PRT (n = 13), placebo/PRT (n = 17), and a control group (n = 10) completed the study. A significant main effect for time occurred for the bench press (p = 0.02), the squat (p < 0.0001), the deadlift (p = 0.001) and the shoulder press (p = 0.02) one-repetition maximum (1RM) in the intervention groups. Conclusion: The PRT program increased maximal strength regardless of whey protein intake. The detraining period demonstrated minimal strength loss, which is beneficial to this population.

The effects of detraining and retraining periods on fat-mass and fat-free mass in elite male soccer players.

The aim of the study was to examine the effects of a detraining period (DTP) (i.e., off-season) with an individually prescribed training program, and a retraining period (RTP) (i.e., pre-season) combining soccer and flywheel-based strength training on fat-free mass (FFM) and fat-mass (FM) in 10 elite professional male soccer players. The present study used a controlled repeated-measures research design to investigate the changes in FFM and FM using dual-energy X-ray absorptiometry. Whole body %FM increased (effect size (ES) = 0.87 ± 0.46) and FFM reduced after DTP (ES = −0.30 ± 0.19), returning to values comparable to the end of the previous season after RTP. At regional levels, arms, legs, and trunk %FM increased (ES = from 0.42 to 1.29) while trunk-FFM was reduced (ES = −0.40 ± 0.26) after DTP, returning to the values observed at the end of the previous season after RTP. Legs-FFM did not change after DTP, with a substantial increase after RTP in comparison with pre-season values (ES = 0.34 ± 0.29 and 0.53 ± 0.36 for the right and left leg, respectively). Despite the small sample size of the present study, the findings indicate that elite soccer players can be allowed 2 weeks of rest during a five-week DTP, since the changes in %FM and FFM were relatively small, and FM and FFM returned to the optimal initial values for competition after the proposed RTP during the pre-season.

Effects of training, detraining, and retraining on strength, hypertrophy, and myonuclear number in human skeletal muscle.

Previously trained mouse muscles acquire strength and volume faster than naïve muscles; it has been suggested that this is related to increased myonuclear density. The present study aimed to determine whether a previously strength-trained leg (mem-leg) would respond better to a period of strength training than a previously untrained leg (con-leg). Nine men and 10 women performed unilateral strength training (T1) for 10 wk, followed by 20 wk of detraining (DT) and a 5-wk bilateral retraining period (T2). Muscle biopsies were taken before and after each training period and analyzed for myonuclear number, fiber volume, and cross-sectional area (CSA). Ultrasound and one repetition of maximum leg extension were performed to determine muscle thickness (MT) and strength. CSA (~17%), MT (~10%), and strength (~20%) increased during T1 in the mem-leg. However, the myonuclear number and fiber volume did not change. MT and CSA returned to baseline values during DT, but strength remained elevated (~60%), supporting previous findings of a long-lasting motor learning effect. MT and strength increased similarly in the mem-leg and con-leg during T2, whereas CSA, fiber volume, and myonuclear number remained unaffected. In conclusion, training response during T2 did not differ between the mem-leg and con-leg. However, this does not discount the existence of human muscle memory, since no increase in the number of myonuclei was detected during T1 and no clear detraining effect was observed for cell size during DT; thus, the present data did not allow for a rigorous test of the muscle memory hypothesis. NEW & NOTEWORTHY If a long-lasting intramuscular memory exists in humans, this will affect strength-training advice for both athletes and the public. Based on animal experiments, we hypothesized that such a memory exists and that it is related to the myonuclear number. However, a period of unilateral strength training, followed by detraining, did not increase the myonuclear number. The training response, during a subsequent bilateral retraining period, was not enhanced in the previously trained leg.

The mechanisms involved in the increased adiposity induced by interruption of regular physical exercise practice

AimsWe investigated the effects of physical detraining on lipogenesis/lipolysis and cellularity (apoptosis/adipogenesis) in rat subcutaneous (inguinal; SC) and visceral (retroperitoneal; RP) white adipose depots. Main methodsThree groups of male Wistar rats (6-wk old) were studied: (1) (T) trained for 12 weeks; (2) (D) trained for 8 weeks and detrained for 4 weeks; and (3) (S) age-matched sedentary. Training consisted of treadmill running sessions (1 h/day, 5 days/week, 50–60% maximal race capacity). Key findingsPhysical detraining increased glucose oxidation, lipogenesis, and adipocyte size in the SC and RP depots. The number of apoptotic SC adipocytes was reduced by 53% in the T (p < 0.0001) and by 43% in the D (p < 0.001) as compared with S. RP adipocyte apoptosis in the T and D was 9.48% and 10.9% greater compared to the S, respectively (p < 0.05). In the SC stromal vascular fraction (SVF) of D rats, adiponectin, sterol regulatory element binding protein (SREBP)-1c, Peroxisome proliferator-activated receptor gamma (PPARγ), and Perilipin A mRNA expressions were more pronounced than S group, suggesting a more intense adipogenesis. This putative adipogenic effect was not observed in the RP depot. The physical detraining promoted rapid increase in the SC and RP depots however not through the same mechanisms. SignificancePhysical detraining induced fat cell hypertrophy (increase of lipogenesis) in both SC and RP whereas hyperplasia (increase of adipogenesis and reduction of apoptosis) was found in SC only. These results indicate the mechanism associated with obesogenic effects of detraining varies with the fat depot.