Detraining: loss of training-induced physiological and performance adaptations. Part II: Long term insufficient training stimulus

Tapering strategies in elite British endurance runners

The aim of the study was to explore pre-competition training practices of elite endurance runners. Training details from elite British middle distance (MD; 800 m and 1500 m), long distance (LD; 3000 m steeplechase to 10,000 m) and marathon (MAR) runners were collected by survey for 7 days in a regular training (RT) phase and throughout a pre-competition taper. Taper duration was [median (interquartile range)] 6 (3) days in MD, 6 (1) days in LD and 14 (8) days in MAR runners. Continuous running volume was reduced to 70 (16)%, 71 (24)% and 53 (12)% of regular levels in MD, LD and MAR runners, respectively (P < 0.05). Interval running volume was reduced compared to regular training (MD; 53 (45)%, LD; 67 (23)%, MAR; 64 (34)%, P < 0.05). During tapering, the peak interval training intensity was above race speed in LD and MAR runners (112 (27)% and 114 (3)%, respectively, P < 0.05), but not different in MD (100 (2)%). Higher weekly continuous running volume and frequency in RT were associated with greater corresponding reductions during the taper (R = -0.70 and R = -0.63, respectively, both P < 0.05). Running intensity during RT was positively associated with taper running intensity (continuous intensity; R = 0.97 and interval intensity; R = 0.81, both P < 0.05). Algorithms were generated to predict and potentially prescribe taper content based on the RT of elite runners. In conclusion, training undertaken prior to the taper in elite endurance runners is predictive of the tapering strategy implemented before competition.

Growth influences biomechanical profile of talented swimmers during the summer break

This study aimed to analyse the effect of growth during a summer break on biomechanical profile of talented swimmers. Twenty-five young swimmers (12 boys and 13 girls) undertook several anthropometric and biomechanical tests at the end of the 2011-2012 season (pre-test) and 10 weeks later at the beginning of the 2012-2013 season (post-test). Height, arm span, hand surface area, and foot surface area were collected as anthropometric parameters, while stroke frequency, stroke length, stroke index, propelling efficiency, active drag, and active drag coefficient were considered as biomechanical variables. The mean swimming velocity during an all-out 25 m front crawl effort was used as the performance outcome. After the 10-week break, the swimmers were taller with an increased arm span, hand, and foot areas. Increases in stroke length, stroke index, propelling efficiency, and performance were also observed. Conversely, the stroke frequency, active drag, and drag coefficient remained unchanged. When controlling the effect of growth, no significant variation was determined on the biomechanical variables. The performance presented high associations with biomechanical and anthropometric parameters at pre-test and post-test, respectively. The results show that young talented swimmers still present biomechanical improvements after a 10-week break, which are mainly explained by their normal growth.

Discrepancy between exercise performance, body composition, and sex steroid response after a six-week detraining period in professional soccer players

Purpose

The aim of this study was to examine the effects of a six-week off-season detraining period on exercise performance, body composition, and on circulating sex steroid levels in soccer players.

Methods

Fifty-five professional male soccer players, members of two Greek Superleague Teams (Team A, n = 23; Team B, n = 22), participated in the study. The first two weeks of the detraining period the players abstained from any physical activity. The following four weeks, players performed low-intensity (50%–60% of VO₂max) aerobic running of 20 to 30 minutes duration three times per week. Exercise performance testing, anthropometry, and blood sampling were performed before and after the six-week experimental period.

Results

Our data showed that in both teams A and B the six-week detraining period resulted in significant reductions in maximal oxygen consumption (60,31±2,52 vs 57,67±2,54; p<0.001, and 60,47±4,13 vs 58,30±3,88; p<0.001 respectively), squat-jump (39,70±3,32 vs 37,30±3,08; p<0.001, and 41,05±3,34 vs 38,18±3,03; p<0.001 respectively), and countermovement-jump (41,04±3,99 vs 39,13±3,26; p<0.001 and 42,82±3,60 vs 40,09±2,79; p<0.001 respectively), and significant increases in 10-meters sprint (1,74±0,063 vs 1,79±0,064; p<0.001, and 1,73±0,065 vs 1,78±0,072; p<0.001 respectively), 20-meters sprint (3,02±0,05 vs 3,06±0,06; p<0.001, and 3,01±0,066 vs 3,06±0,063; p<0.001 respectively), body fat percentage (Team A; p<0.001, Team B; p<0.001), and body weight (Team A; p<0.001, Team B; p<0.001). Neither team displayed any significant changes in the resting concentrations of total-testosterone, free-testosterone, dehydroepiandrosterone-sulfate, Δ4-androstenedione, estradiol, luteinizing hormone, follicle-stimulating hormone, and prolactin. Furthermore, sex steroids levels did not correlate with exercise performance parameters.

Conclusion

Our results suggest that the six-week detraining period resulted in a rapid loss of exercise performance adaptations and optimal body composition status, but did not affect sex steroid resting levels. The insignificant changes in sex steroid concentration indicate that these hormones were a non-contributing parameter for the observed negative effects of detraining on exercise performance and body composition.

The Injury/Illness Performance Project (IIPP): A Novel Epidemiological Approach for Recording the Consequences of Sports Injuries and Illnesses

Background. Describing the frequency, severity, and causes of sports injuries and illnesses reliably is important for quantifying the risk to athletes and providing direction for prevention initiatives. Methods. Time-loss and/or medical-attention definitions have long been used in sports injury/illness epidemiology research, but the limitations to these definitions mean that some events are incorrectly classified or omitted completely, where athletes continue to train and compete at high levels but experience restrictions in their performance. Introducing a graded definition of performance-restriction may provide a solution to this issue. Results. Results from the Great Britain injury/illness performance project (IIPP) are presented using a performance-restriction adaptation of the accepted surveillance consensus methodologies. The IIPP involved 322 Olympic athletes (males: 172; female: 150) from 10 Great Britain Olympic sports between September 2009 and August 2012. Of all injuries (n = 565), 216 were classified as causing time-loss, 346 as causing performance-restriction, and 3 were unclassified. For athlete illnesses (n = 378), the majority (P < 0.01) resulted in time-loss (270) compared with performance-restriction (101) (7 unclassified). Conclusions. Successful implementation of prevention strategies relies on the correct characterisation of injury/illness risk factors. Including a performance-restriction classification could provide a deeper understanding of injuries/illnesses and better informed prevention initiatives.

Practice habits and attitudes and behaviors concerning shoulder pain in high school competitive club swimmers

OBJECTIVE

The objective of this study is to describe the practice habits, injury frequency, and attitudes and behaviors concerning shoulder pain in high school-aged competitive swimmers and describe the relationship between attitudes and behaviors.

DESIGN

Cross-sectional research design.

SETTING

Local swimming clubs.

PARTICIPANTS

One hundred two swimmers, aged 13-18 years, at the top training level of their club team were included in the study.

ASSESSMENT OF RISK FACTORS

Participants were given a survey with questions regarding swimming practice and attitudes and behaviors concerning shoulder pain.

MAIN OUTCOME MEASURES

Practice habits (yards/week, practice/week, dry-land and weight/week, and months swimming/year) and attitudes and behaviors concerning shoulder pain.

RESULTS

Subjects completed an average of 6.89 ± 1.41 swimming practices/wk of 6000 to 7000 yd/practice. The majority of swimmers believe that mild and moderate shoulder pain is normal in swimming and should be tolerated to complete practice, while a majority responded that they swim with shoulder pain. Seventy-three percent of swimmers reported using pain medication to manage their shoulder pain. There was a significant correlation between attitude and behaviors of moderate and severe shoulder pain.

CONCLUSIONS

Club swimmers have a high frequency of practices, comparable to collegiate and professional swimmers. They believe that shoulder pain is normal and should be tolerated to complete practice. The association between the swimmers' attitudes and behaviors indicates that the interventions that educate the swimmers, coaches, and parents may be effective in changing their attitudes and ultimately their behaviors, decreasing the number of athletes who train with shoulder pain.

Longitudinal changes in cardiac autonomic function and aerobic fitness indices in endurance runners: a case study with a high-level team

To determine the effects of preparatory phase training on aerobic parameters, resting heart rate variability (HRV) and 5-km performance of high-level endurance runners and the relationship between the percentage change (% change) of resting HRV with the % change of aerobic parameters and 5-km performance. Six runners were assessed before and after seven weeks of training. The aerobic parameters were determined in an incremental test. The HRV was assessed by a heart rate monitor. Athletes performed a 5-km running test in a track. The analysis revealed 'likely' and 'very likely' improvements for velocity associated with maximal oxygen uptake ([Formula: see text]O2max) (20.0±1.0 km·h(-1) to 21.2±0.6 km·h(-1)) and 5-km performance (18.0±0.4 km·h(-1) to 18.9±0.7 km·h(-1)), respectively, as well as 'likely' decrease in high frequency (41.4±18.5 nu to 30.4±14.3 nu), and increase in low frequency (58.5±18.5 nu to 69.6±14.3 nu) band densities. The variation in the velocity associated with [Formula: see text]O2max showed the highest correlation with 5-km performance (r=0.95). The % change in the square root of the mean sum of the squared differences between R-R intervals and standard deviation 1 were highly correlated with variation in 5-km performance (r=0.69 and 0.66). Changes in the velocity associated with [Formula: see text]O2max and vagally mediated HRV were highly associated with 5-km running performance within the investigated team. These results have important implications because these parameters can be assessed longitudinally to monitor adaptation to training.

Effect of training cessation on muscular performance: a meta-analysis

The purpose of this study was to assess the effect of resistance training cessation on strength performance through a meta-analysis. Seven databases were searched from which 103 of 284 potential studies met inclusion criteria. Training status, sex, age, and the duration of training cessation were used as moderators. Standardized mean difference (SMD) in muscular performance was calculated and weighted by the inverse of variance to calculate an overall effect and its 95% confidence interval (CI). Results indicated a detrimental effect of resistance training cessation on all components of muscular performance: [submaximal strength; SMD (95% CI) = -0.62 (-0.80 to -0.45), P < 0.01], [maximal force; SMD (95% CI) = -0.46 (-0.54 to -0.37), P < 0.01], [maximal power; SMD (95% CI) = -0.20 (-0.28 to -0.13), P < 0.01]. A dose-response relationship between the amplitude of SMD and the duration of training cessation was identified. The effect of resistance training cessation was found to be larger in older people (> 65 years old). The effect was also larger in inactive people for maximal force and maximal power when compared with recreational athletes. Resistance training cessation decreases all components of muscular strength. The magnitude of the effect differs according to training status, age or the duration of training cessation.

Effects of in-season strength maintenance training frequency in professional soccer players

The aim of the present study was to examine the effect of in-season strength maintenance training frequency on strength, jump height, and 40-m sprint performance in professional soccer players. The players performed the same strength training program twice a week during a 10-week preparatory period. In-season, one group of players performed 1 strength maintenance training session per week (group 2 + 1; n = 7), whereas the other group performed 1 session every second week (group 2 + 0.5; n = 7). Only the strength training frequency during the in-season differed between the groups, whereas the exercise, sets and number of repetition maximum as well as soccer sessions were similar in the 2 groups. The preseason strength training resulted in an increased strength, sprint, and jump height (p < 0.05). During the first 12 weeks of the in-season, the initial gain in strength and 40-m sprint performance was maintained in group 2 + 1, whereas both strength and sprint performance were reduced in group 2 + 0.5 (p < 0.05). There was no statistical significant change in jump height in any of the 2 groups during the first 12 weeks of the in-season. In conclusion, performing 1 weekly strength maintenance session during the first 12 weeks of the in-season allowed professional soccer players to maintain the improved strength, sprint, and jump performance achieved during a preceding 10-week preparatory period. On the other hand, performing only 1 strength maintenance session every second week during the in-season resulted in reduced leg strength and 40-m sprint performance. The practical recommendation from the present study is that during a 12-week period, 1 strength maintenance session per week may be sufficient to maintain initial gain in strength and sprint performance achieved during a preceding preparatory period.

Detraining-induced alterations in metabolic and fitness markers after a multicomponent exercise-training program in older men

The aim of the present study was to investigate the effects of a 8-week detraining period after a 16-week multicomponent training program including strength and aerobic exercises on the main determinants of aerobic fitness, muscle strength and some metabolic markers in 24 older subjects (60.2 ± 3.0 years). The oxygen uptake at the second ventilatory threshold (VO2VT2) and at the end of exercise (VO2max), maximum voluntary contraction force (MVC) of knee extensors and some metabolic indexes, i.e., insulin sensitivity, blood lipid profile, inflammatory cytokines, and endothelial function, were evaluated at baseline and after the training and detraining periods. The training program induced significant improvements in VO2VT2 (16%, p < 0.05), VO2max (14%, p < 0.05), MVC (6.5%, p < 0.05), insulin sensitivity (16%, p < 0.05), and endothelial function (p < 0.05) but induced no significant change in lipid profile and inflammatory cytokines. Interestingly, VO2VT2 and VO2max (mL·min–1·kg–1) scores remained significantly above pretraining values after the 8-week detraining period. However, the detraining period reversed MVC values, the insulin sensitivity and endothelial function to baseline levels. To conclude, the 8-week detraining partially reversed the major components of aerobic fitness but totally abolished the gains in muscle strength and some metabolic indexes after a 16-week multicomponent training program in older men. Taken as a whole, the results of this study emphasize the importance of exercise prescriptions for older subjects and the need not to interrupt exercise-training over a prolonged period.

The effects of detraining on blood adipokines and antioxidant enzyme in Korean overweight children

The present study examined the change to clarify the effects of detraining on the concentration of lipid profiles, serum adipokines and antioxidant enzyme gene expression in Korean overweight children. The subjects were normal children (n = 19) and obese children (n = 20) who were further subdivided into the overweight training (OT) group (n = 10) and the overweight detraining (OD) group (n = 10). Maximal oxygen uptake (VO(2)max); body composition; lipid profiles (TG, TC); adipokines (adiponectin and leptin); antioxidants (blood and gene expressions SOD and GPX) were measured before, 12 weeks, and 24 weeks after the exercise program. Body mass index (BMI) and %fat were significantly higher in the OD group only. However, waist hip ration (WHR) and systolic blood pressure (SBP) were significantly decreased in the OT group. TG was significantly decreased in the OT group. There was a significant difference in TG level between the two groups. Besides, adiponectin was significantly increased in both the OT group and the OD group. Furthermore, leptin was significantly decreased in the OT group. There was a significant difference in leptin level between the two groups. In training groups, the expression of SOD was significantly increased after a 12- and 24-week period (p < 0.05). However, detraining group was significantly increased after a 12-week only (p < 0.05). In addition, GPX was significantly increased after a 24-week only in the training group (p < 0.05). Thus, detraining showed that negative effected on body composition and lipid profiles and maintained of uniform period on adipokines and antioxidant enzyme the protein and expression.

Triceps brachii strength and regional body composition changes after detraining quantified by MRI

PURPOSE

To determine the triceps brachii functional adaptation and regional body composition changes after 12 months of detraining.

MATERIALS AND METHODS

Seventeen healthy young men (22.2 ± 1.0 y, body mass index 24.9 ± 3.1 kg/m(2) ) were put in the detraining regimen for 12 months after completing a 12-week exercise protocol on isoacceleration dynamometer (5 times a week, 5 daily series with 10 maximal elbow extensions, 1 min rest between sets). Triceps brachii muscle strength was measured by isoacceleration dynamometry, using identical protocol as during the training. Muscle volumes, subcutaneous adipose tissue (SCAT), and intermuscular adipose tissue (IMAT) at mid-humerus were assessed by using MRI.

RESULTS

Long-term detraining resulted in the significant decrease of 17% and 19% in endurance strength and fatigue rate, respectively. Maximal muscle strength slightly changed, and its 4% decrease was not significant. Triceps brachii volumes of both arms returned to their pretraining values (475.7 ± 54.91 cm(3) for right arm, and 483.9 ± 77.5 cm(3) for left arm). IMAT depots in upper arm significantly increased by 14% after 12 months of detraining, when compared with baseline values (P < 0.05).

CONCLUSION

Long-term detraining leads to triceps brachii adaptation with endurance strength decrease, volume return to its baseline values, and significant IMAT accumulation. IMAT values after 12 months of detraining exceed baseline, pretraining values, which is significant accumulation as a result of physiologically decreased muscle activity.

Protein and Amino Acid Supplementation Does Not Alter Proteolytic Gene Expression following Immobilization

Objective. To determine if supplementation of protein and amino acids (PAA) decreases skeletal muscle expression of atrophy-related genes, muscle mass, and strength during immobilization in humans. Methods. Twenty males wore a lower-limb immobilization boot for 28 days and consumed either a PAA supplement (28 g protein) or carbohydrate placebo (28 g maltodextrose), while consuming their normal daily diet. Testing sessions included dietary analysis, lower-leg girth and body composition measurements, strength testing, and gastrocnemius muscle biopsies. Muscle was analyzed for mRNA expression of markers in the ubiquitin and calpain systems, myostatin, TNF-α, and NF-κB. Results. All genes of interest increased over time (P < .05), but there was no difference between groups. Lower-leg girth decreased over time (P = 0.02); however, there were no significant changes in body composition or strength. Conclusion. Short-term lower-limb disuse, despite the absence of significant muscle atrophy, is associated with increases in skeletal muscle gene expression of several proteolysis-related genes. These changes do not appear to be altered by oral PAA supplementation.

The effects of plyometric training followed by detraining and reduced training periods on explosive strength in adolescent male basketball players

The aims of this study were to determine the effects of (a) plyometric training on explosive strength indicators in adolescent male basketball players and (b) detraining and reduced training on previously achieved explosive strength gains. Two groups were formed: an experimental and a control group. The former was submitted to a 10-week in-season plyometric training program, twice weekly, along with regular basketball practice. Simultaneously, the control group participated in regular basketball practice only. At the end of this period, the experimental group was subdivided into 2 groups: a reduced training group and a detraining group. All participants were assessed on squat jump, countermovement jump, Abalakov test, depth jump, mechanical power, and medicine ball throw at the beginning and at the end of the 10-week in-season plyometric training and on weeks 4, 8, 12, and 16 of the in-season detraining and reduced training periods. In the first phase of the study, the experimental group significantly increased all the assessed indicators (p < 0.05). In the following phase and in general all the groups maintained the previously achieved results. In conclusion, plyometric training showed positive effects on upper- and lower-body explosive strength in adolescent male basketball players. Moreover, we can state that both detraining and a reduced training program indistinctly contribute to maintenance of strength levels. These results highlight the unique power that basketball-specific training seems to have on the sustainability and maintenance of sport performance.

Physiological effects of tapering and detraining in world-class kayakers

PURPOSE

This study analyzed changes in neuromuscular, body composition, and endurance markers during 4 wk of tapering and subsequent 5 wk of reduced training (RT) or training cessation (TC).

METHODS

Fourteen world-class kayakers were randomly assigned to either a TC (n = 7) or an RT group (n = 7). One-repetition maximum (1RM) strength, mean concentric velocity with 45% 1RM (V45%) in the bench press (BP) and prone bench pull (PBP) exercises, and body composition assessments were conducted at the start (T0) and end (T1) of a 43-wk training program, after tapering for the world championships (T2) and after TC or RT (T3). A graded exercise test on a kayak ergometer for determination of maximal oxygen uptake at T0, T1, and T3 was also performed.

RESULTS

After tapering, no significant changes were observed in 1RM or V45%. TC resulted in significantly greater declines in 1RM strength (-8.9% and -7.8%, P < 0.05, respectively, for BP and PBP) than those observed for RT (-3.9% and -3.4%). Decreases in V45% in BP and PBP were larger for TC (-12.6% and -10.0%) than for RT (-9.0% and -6.7%). Increases in sum of eight skinfolds were observed after both TC and RT, whereas declines in maximal aerobic power were lower for RT (-5.6%) than for TC (-11.3%).

CONCLUSIONS

Short-term TC results in large decreases in maximal strength and especially V45% in highly trained athletes. These results suggest the need of performing a minimal maintenance program to avoid excessive declines in neuromuscular function in cases where a prolonged break from training is required.

In-season strength maintenance training increases well-trained cyclists' performance

We investigated the effects of strength maintenance training on thigh muscle cross-sectional area (CSA), leg strength, determinants of cycling performance, and cycling performance. Well-trained cyclists completed either (1) usual endurance training supplemented with heavy strength training twice a week during a 12-week preparatory period followed by strength maintenance training once a week during the first 13 weeks of a competition period (E + S; n = 6 [♂ = 6]), or (2) usual endurance training during the whole intervention period (E; n = 6 [♂ = 5, ♀ = 1]). Following the preparatory period, E + S increased thigh muscle CSA and 1RM (p < 0.05), while no changes were observed in E. Both groups increased maximal oxygen consumption and mean power output in the 40-min all-out trial (p < 0.05). At 13 weeks into the competition period, E + S had preserved the increase in CSA and strength from the preparatory period. From the beginning of the preparatory period to 13 weeks into the competition period, E + S increased peak power output in the Wingate test, power output at 2 mmol l(-1) [la(-)], maximal aerobic power output (W (max)), and mean power output in the 40-min all-out trial (p < 0.05). The relative improvements in the last two measurements were larger than in E (p < 0.05). For E, W (max) and power output at 2 mmol l(-1) [la(-)] remained unchanged. In conclusion, in well-trained cyclists, strength maintenance training in a competition period preserved increases in thigh muscle CSA and leg strength attained in a preceding preparatory period and further improved cycling performance determinants and performance.

Rapid vascular modifications to localized rhythmic handgrip training and detraining: vascular conditioning and deconditioning

Despite the evidence describing the rapid vascular function modifications to commencement and cessation of large muscle exercises (i.e. cycling), no studies examined the time-course vascular modifications to localized training and detraining. This study aimed to examine the effects of 4-week rhythmic handgrip exercise training and 2-week detraining on reactive hyperemic forearm blood flow and vascular resistance in 11 young men. Rhythmic handgrip exercise was performed in the non-dominant forearm for 20 min/day, 5 days/week, at 60% of maximum voluntary contraction for 4 weeks, followed by 2 weeks of no training. Forearm blood flow and vascular resistance were evaluated, in both arms, at rest and following arterial occlusion. These vascular function indices were obtained in five visits; before, after 1 and 4 week(s) of training as well as after 1 and 2 week(s) of training cessation. Resting cardiovascular measures were not altered during the study period. A 2 (arms) x 5 (visits) ANOVA revealed significant arms-by-visits interactions for reactive hyperemic forearm blood flow (p = 0.02) and vascular resistance (p = 0.02). Subsequent comparison demonstrated increased trained forearm reactive hyperemic blood flow 1 week after training, then returned to pre-training values 1 week following training cessation. In contrast, vascular resistance decreased 1 week after training commencement, only to return to pretraining level 1 week after training cessation. These results indicate a rapid, unilateral improvement in regional reactive hyperemic blood flow and vascular resistance following localized exercise-training. However, the improvements are transient and return to pretraining levels 1 week after detraining.

Training modalities: impact on endurance capacity

Endurance athletes demonstrate an exceptional resistance to fatigue when exercising at high intensity. Much research has been devoted to the contribution of aerobic capacity for the economy of endurance performance. Important aspects of the fine-tuning of metabolic processes and power output in the endurance athlete have been overlooked. This review addresses how training paradigms exploit bioenergetic pathways in recruited muscle groups to promote the endurance phenotype. A special focus is laid on the genome-mediated mechanisms that underlie the conditioning of fatigue resistance and aerobic performance by training macrocycles and complements. The available data on work-induced muscle plasticity implies that different biologic strategies are exploited in athletic and untrained populations to boost endurance capacity. Olympic champions are probably endowed with a unique constitution that renders the conditioning of endurance capacity for competition particularly efficient.

Effects of reduced training and detraining on upper and lower body explosive strength in adolescent male basketball players

The purpose of this study was to assess and compare the effects of detraining and of a reduced training program on upper- and lower-body explosive strength in adolescent male basketball players. To study this, 15 subjects, aged 14 to 15 years old, were randomly assigned to 1 of the 2 following groups: reduced training (RT; n = 8) and detraining (DTR; n = 7). The participants were assessed on squat jump (SJ), countermovement jump (CMJ), Abalakov test (ABA), depth jump (DJ), mechanical power (MP), and medicine ball throw (MBT) after a 10-week in-season complex training program (T0) and at the end of 4 (T4), 8 (T8), 12 (T12), and 16 (T16) weeks of detraining and of the reduced training periods. Both groups showed maintenance of explosive strength values and statistical similarity between them whatever the moment of evaluation. In conclusion, 16 weeks of detraining or of reduced training allow for the maintenance of the gains previously achieved by the application of a 10-week in-season complex training program. However, the lack of differences between detraining and reduced training leads to the conclusion that regular basketball practice can sustain by itself the previously achieved explosive strength gains, considering its mainly explosive characteristics.

Long-term follow-up of a high-intensity exercise program in patients with rheumatoid arthritis

The aims of this study were to describe rheumatoid arthritis patients' compliance with continued exercise after participation in a 2-year supervised high-intensity exercise program and to investigate if the initially achieved effectiveness and safety were sustained. Data were gathered by follow-up of the participants who completed the 2-year high-intensity intervention in a randomized controlled trial (Rheumatoid Arthritis Patient In Training study). Eighteen months thereafter, measurements of compliance, aerobic capacity, muscle strength, functional ability, disease activity, and radiological damage of the large joints were performed. Seventy-one patients were available for follow-up at 18 months, of whom 60 (84%) were still exercising (exercise group: EG), with average similar intensity but at a lower frequency as the initial intervention. Eleven patients (16%) reported low intensity or no exercises (no-exercise group: no-EG). Patients in the EG had better aerobic fitness and functional ability, lower disease activity, and higher attendance rate after the initial 2-year intervention. At follow-up, both groups showed a deterioration of aerobic fitness and only patients in the EG were able to behold their muscle strength gains. Functional ability, gained during the previous participation in high-intensity exercises, remained stable in both groups. Importantly, no detrimental effects on disease activity or radiological damage of the large joints were found in either group. In conclusion, the majority of the patients who participated in the 24-month high-intensity exercise program continued exercising in the ensuing 18 months. In contrast to those who did not continue exercising, they were able to preserve their gains in muscle strength without increased disease activity or progression of radiological damage.

Detraining and retraining in older adults following long-term muscle power or muscle strength specific training

BACKGROUND

Training cessation among older adults is associated with the loss of functional ability. However, exercise programs undertaken prior to activity cessation may offer functional protection. In the present study, the residual effects of muscle power or muscle strength training were investigated following extended detraining and subsequent retraining.

METHODS

Thirty-eight healthy independent older adults (65-84 years) entered a 24-week detraining period subsequent to 24 weeks of training. Following detraining, participants recommenced training using either the high-velocity muscle power (HV) or muscle strength (ST) protocol, as undertaken during the initial training period, twice weekly for 12 weeks. Isometric and dynamic muscle strength, muscle power, movement velocity, muscle endurance, electromyographic activity, and the results of a battery of functional performance tasks were assessed.

RESULTS

Muscle function and functional performance increased following initial training, however, no group differences were observed. Detraining resulted in similar declines in muscle power and muscle strength for both groups (p <.05) (power, HV 17.8 +/- 1.8%, ST 15.5 +/- 2.2%; and strength, HV 17.1 +/- 2.2%, ST 16.5 +/- 1.8%), with comparable accrual following retraining. No significant changes in functional ability were observed following detraining (average change; HV 3.1 +/- 3.5% and ST 2.1 +/- 3.5%) or retraining. No group differences emerged in this study.

CONCLUSION

Cessation of training resulted in only a modest loss of muscle power and strength that was recouped following 12 weeks of retraining. Importantly, training-induced gains in functional performance were preserved during detraining. The residual effects of power or strength training appear comparable, and both may be suitable exercise modes prior to a period of activity cessation to promote physical independence.

Effects of Tapering on Performance

PURPOSE

The purpose of this investigation was to assess the effects of alterations in taper components on performance in competitive athletes, through a meta-analysis.

METHODS

Six databases were searched using relevant terms and strategies. Criteria for study inclusion were that participants must be competitive athletes, a tapering intervention must be employed providing details about the procedures used to decrease the training load, use of actual competition or field-based criterion performance, and inclusion of all necessary data to calculate effect sizes. Datasets reported in more than one published study were only included once in the present analyses. Twenty-seven of 182 potential studies met these criteria and were included in the analysis. The dependent variable was performance, and the independent variables were the decrease in training intensity, volume, and frequency, as well as the pattern of the taper and its duration. Pre-post taper standardized mean differences in performance were calculated and weighted according to the within-group heterogeneity to develop an overall effect.

RESULTS

The optimal strategy to optimize performance is a tapering intervention of 2-wk duration (overall effect = 0.59 +/- 0.33, P < 0.001), where the training volume is exponentially decreased by 41-60% (overall effect = 0.72 +/- 0.36, P < 0.001), without any modification of either training intensity (overall effect = 0.33 +/- 0.14, P < 0.001) or frequency (overall effect = 0.35 +/- 0.17, P < 0.001).

CONCLUSION

A 2-wk taper during which training volume is exponentially reduced by 41-60% seems to be the most efficient strategy to maximize performance gains. This meta-analysis provides a framework that can be useful for athletes, coaches, and sport scientists to optimize their tapering strategy.

Improvement of VO2max by cardiac output and oxygen extraction adaptation during intermittent versus continuous endurance training

Improvement of exercise capacity by continuous (CT) versus interval training (IT) remains debated. We tested the hypothesis that CT and IT might improve peripheral and/or central adaptations, respectively, by randomly assigning 10 healthy subjects to two periods of 24 trainings sessions over 8 weeks in a cross-over design, separated by 12 weeks of detraining. Maximal oxygen uptake (VO2max), cardiac output (Qmax) and maximal arteriovenous oxygen difference (Da-vO2max) were obtained during an exhaustive incremental test before and after each training period. VO2max and Qmax increased only after IT (from 26.3 +/- 1.6 to 35.2 +/- 3.8 ml min(-1) kg(-1) and from 17.5 +/- 1.3 to 19.5 +/- 1.8 l min(-1), respectively; P < 0.01). Da-vO2max increased after both protocols (from 11.0 +/- 0.8 to 12.7 +/- 1.0; P < 0.01 and from 11.0 +/- 0.8 to 12.1 +/- 1.0 ml 100 ml(-1), P < 0.05 in CT and IT, respectively). At submaximal intensity a significant rightward shift of the Q/Da-vO2 relationship appeared only after CT. These results suggest that in isoenergetic training, central and peripheral adaptations in oxygen transport and utilization are training-modality dependant. IT improves both central and peripheral components of Da-vO2max whereas CT is mainly associated with greater oxygen extraction.

Effect of high-intensity interval training and detraining on extra $${\dot{{V}}\hbox{O}_{2}}$$ and on the $${\dot{{V}}\hbox{O}_{2}}$$ slow component

To examine the effect of 6-week of high-intensity interval training (HIT) and of 6-week of detraining on the VO2/Work Rate (WR) relationship and on the slow component of VO2, nine young male adults performed on cycle ergometer, before, after training and after detraining, an incremental exercise (IE), and a 6-min constant work rate exercise (CWRE) above the first ventilatory threshold (VT1). For each IE, the slope and the intercept of the VO2/WR relationship were calculated with linear regression using data before VT1. The difference between VO2max measured and VO2max expected using the pre-VT1 slope was calculated (extra VO2). The difference between VO2 at 6th min and VO2 at 3rd min during CWRE (DeltaVO2(6'-3')) was also determined. HIT induced significant improvement of most of the aerobic fitness parameters while most of these parameters returned to their pre-training level after detraining. Extra VO2 during IE was reduced after training (130 +/- 100 vs. -29 +/- 175 ml min(-1), P = 0.04) and was not altered after detraining compared to post-training. DeltaVO2(6'-3') during CWRE was unchanged by training and by detraining. We found a significant correlation (r2 = 0.575, P = 0.02) between extra VO2 and DeltaVO2(6'-3') before training. These results show that an alteration of extra VO2 can occur without any change in the VO2 slow component, suggesting a possible dissociation of the two phenomena. Moreover, the fact that extra VO2 did not change after detraining could indicate that this improvement may remain after the loss of other adaptations.

Muscle adaptation to altitude: tissue capillarity and capacity for aerobic metabolism

Prolonged exposure to high altitude leads to reduced muscle mass and performance. The fall in muscle mass follows a reduction in fiber size, which at first was believed to be accompanied by increased fiber capillarization and aerobic enzymes. Subsequent studies showed that hypoxia alone does not alter capillary number and geometry in skeletal muscles of mammals at altitude. It was also found that alterations in fiber size and aerobic enzymes depend on a number of additional factors, including animal activity and the level of hypoxia (e.g., moderate vs. extreme altitude). With training at altitude, fiber capillary number and aerobic enzymes are increased, indicating that muscle potential for plasticity is conserved in hypoxia. Recent studies have also shown that capillary number and geometry are altered in muscles of several species of birds native or exposed to higher altitude; that is, that capillary growth can occur in skeletal muscle in response to chronic exposure to high altitude. In this mini review, we summarize these data and current knowledge on muscle capillary to fiber structural relationships and their implications for muscle aerobic function at altitude.

Cardiorespiratory and metabolic characteristics of detraining in humans

Detraining can be defined as the partial or complete loss of training-induced adaptations, in response to an insufficient training stimulus. Detraining is characterized, among other changes, by marked alterations in the cardiorespiratory system and the metabolic patterns during exercise. In highly trained athletes, insufficient training induces a rapid decline in VO2max, but it remains above control values. Exercise heart rate increases insufficiently to counterbalance the decreased stroke volume resulting from a rapid blood volume loss, and maximal cardiac output is thus reduced. Cardiac dimensions are also reduced, as well as ventilatory efficiency. Consequently, endurance performance is also markedly impaired. These changes are more moderate in recently trained subjects in the short-term, but recently acquired VO2max gains are completely lost after training stoppage periods longer than 4 wk. From a metabolic viewpoint, even short-term inactivity implies an increased reliance on carbohydrate metabolism during exercise, as shown by a higher exercise respiratory exchange ratio. This may result from a reduced insulin sensitivity and GLUT-4 transporter protein content, coupled with a lowered muscle lipoprotein lipase activity. These metabolic changes may take place within 10 d of training cessation. Resting muscle glycogen concentration returns to baseline within a few weeks without training, and trained athletes' lactate threshold is also lowered, but still remains above untrained values.