Perceived training intensity and performance changes quantification in judo

The objective of this study was to determine the methods of quantification for training and performance, which would be the most appropriate for modeling the responses to long-term training in cadet and junior judo athletes. For this, 10 young male judo athletes (15.9 ± 1.3 years, 64.9 ± 10.3 kg, and 170.8 ± 5.4 cm) competing at a regional/state level volunteered to take part in this study. Data were collected during a 2-year training period (i.e., 702 days) from January 2011 to December 2012. Their mean training volume was 6.52 ± 0.43 hours per week during the preparatory periods and 4.75 ± 0.49 hours per week during the competitive periods. They followed a training program prescribed by the same coach. The training load (TL) was quantified through the session rating of perceived exertion (RPE) and expressed in arbitrary unit (a.u.). Performance was quantified from 5 parameters and divided into 2 categories: performance in competition and performance in training. The evaluation of performance in competition was based on the number of points per level. Performance in training was assessed through 4 different tests. A physical test battery consisting of a standing long jump, 2 judo-specific tests that were the maximal number of dynamic chin-up holding the judogi, and the Special Judo Fitness Test was used. System modeling for describing training adaptations consisted of mathematically relating the TL of the training sessions (system input) to the change in performance (system output). The quality of the fit between TL and performance was similar, whether the TL was computed directly from RPE (R = 0.55 ± 0.18) or from the session RPE (R = 0.56 ± 0.18) and was significant in 8 athletes over 10, excluding the standing jump from the computation of the TL, leading to a simplest method. Thus, this study represents a first attempt to model TL effects on judo-specific performance and has shown that the best relationships between amounts of training and changes in performance were obtained when training amounts were quantified simply from RPE.

Chronic clenbuterol treatment compromises force production without directly altering skeletal muscle contractile machinery

Clenbuterol is a β2 -adrenergic receptor agonist known to induce skeletal muscle hypertrophy and a slow-to-fast phenotypic shift. The aim of the present study was to test the effects of chronic clenbuterol treatment on contractile efficiency and explore the underlying mechanisms, i.e. the muscle contractile machinery and calcium-handling ability. Forty-three 6-week-old male Wistar rats were randomly allocated to one of six groups that were treated with either subcutaneous equimolar doses of clenbuterol (4 mg kg(-1) day(-1) ) or saline solution for 9, 14 or 21 days. In addition to the muscle hypertrophy, although an 89% increase in absolute maximal tetanic force (Po ) was noted, specific maximal tetanic force (sPo) was unchanged or even depressed in the slow twitch muscle of the clenbuterol-treated rats (P < 0.05). The fit of muscle contraction and relaxation force kinetics indicated that clenbuterol treatment significantly reduced the rate constant of force development and the slow and fast rate constants of relaxation in extensor digitorum longus muscle (P < 0.05), and only the fast rate constant of relaxation in soleus muscle (P < 0.05). Myofibrillar ATPase activity increased in both relaxed and activated conditions in soleus (P < 0.001), suggesting that the depressed specific tension was not due to the myosin head alteration itself. Moreover, action potential-elicited Ca(2+) transients in flexor digitorum brevis fibres (fast twitch fibres) from clenbuterol-treated animals demonstrated decreased amplitude after 14 days (-19%, P < 0.01) and 21 days (-25%, P < 0.01). In conclusion, we showed that chronic clenbuterol treatment reduces contractile efficiency, with altered contraction and relaxation kinetics, but without directly altering the contractile machinery. Lower Ca(2+) release during contraction could partially explain these deleterious effects.

Autophagy and protein turnover signaling in slow-twitch muscle during exercise

PURPOSE

The aim of this study was to characterize skeletal muscle protein breakdown and mitochondrial dynamics markers at different points of endurance exercise.

METHODS

Mice run at 10 m·min(-1) during 1 h, and running speed was increased by 0.5 m·min(-1) every minute during 40 min and then by 1 m·min(-1) until exhaustion. Animals were killed by cervical dislocation at 30, 60, 90, and 120 min; at time to exhaustion (Te); and at 3 and 24 h during recovery. The soleus and the deep red regions of the quadriceps muscles were pooled.

RESULTS

AMPK phosphorylation (Thr172) increased from 30 min to Te, and FoxO3a phosphorylation (Thr32 and Ser253) decreased from 120 min to 3 h after exercise. FoxO3a-dependent E3 ligases Mul1 and MuRF1 proteins increased from 30 min to Te and at Te and 3 h after exercise, respectively, whereas MAFbx/atrogin-1 protein expression did not change significantly. The autophagic markers LC3B-II increased at 120 min and Te, and p62 significantly decreased at Te. The AMPK-dependent phosphorylation of Ulk1 at Ser317 and Ser555 increased from 60 min to Te and at 30 and 60 min, respectively. Akt (Ser473), MTOR (Ser2448), and 4E-BP1 (Thr37/46) phosphorylation decreased from 90 min to Te, and the MTOR-dependent phosphorylation of Ulk1 (Ser757) decreased from 120 min to Te. Ser616 phosphorylation of the mitochondrial fission marker DRP1 increased from 60 min to Te, but protein expression of the fusion markers mitofusin-2, a substrate of Mul1, and OPA1 did not significantly change.

CONCLUSIONS

These results fit with a regulation of protein breakdown triggered by FoxO3a and Ulk1 pathways after AMPK activation and Akt/MTOR inhibition. Furthermore, our data suggest that mitochondrial fission is quickly increased, and mitochondrial fusion is unchanged during exercise.

Autophagy is essential to support skeletal muscle plasticity in response to endurance exercise

Physical exercise is a stress that can substantially modulate cellular signaling mechanisms to promote morphological and metabolic adaptations. Skeletal muscle protein and organelle turnover is dependent on two major cellular pathways: Forkhead box class O proteins (FOXO) transcription factors that regulate two main proteolytic systems, the ubiquitin-proteasome, and the autophagy-lysosome systems, including mitochondrial autophagy, and the MTORC1 signaling associated with protein translation and autophagy inhibition. In recent years, it has been well documented that both acute and chronic endurance exercise can affect the autophagy pathway. Importantly, substantial efforts have been made to better understand discrepancies in the literature on its modulation during exercise. A single bout of endurance exercise increases autophagic flux when the duration is long enough, and this response is dependent on nutritional status, since autophagic flux markers and mRNA coding for actors involved in mitophagy are more abundant in the fasted state. In contrast, strength and resistance exercises preferentially raise ubiquitin-proteasome system activity and involve several protein synthesis factors, such as the recently characterized DAGK for mechanistic target of rapamycin activation. In this review, we discuss recent progress on the impact of acute and chronic exercise on cell component turnover systems, with particular focus on autophagy, which until now has been relatively overlooked in skeletal muscle. We especially highlight the most recent studies on the factors that can impact its modulation, including the mode of exercise and the nutritional status, and also discuss the current limitations in the literature to encourage further works on this topic.

The role of AMP-activated protein kinase in the coordination of skeletal muscle turnover and energy homeostasis

The AMP-activated protein kinase (AMPK) is a serine/threonine protein kinase that acts as a sensor of cellular energy status switch regulating several systems including glucose and lipid metabolism. Recently, AMPK has been implicated in the control of skeletal muscle mass by decreasing mTORC1 activity and increasing protein degradation through regulation of ubiquitin-proteasome and autophagy pathways. In this review, we give an overview of the central role of AMPK in the control of skeletal muscle plasticity. We detail particularly its implication in the control of the hypertrophic and atrophic signaling pathways. In the light of these cumulative and attractive results, AMPK appears as a key player in regulating muscle homeostasis and the modulation of its activity may constitute a therapeutic potential in treating muscle wasting syndromes in humans.

Influence of a conservative sleep management strategy during a solo Pacific Ocean crossing on anxiety and perceived fatigue: a case study

The aim of this case study was to determine whether a sailor's deliberate choice of a conservative strategy to manage sleep deprivation would allow him to cross the Pacific Ocean and to minimize his state of anxiety and perceived fatigue. The participant, who had more than 10 years' sailing experience in severe conditions, was tested on a small catamaran without any living quarters during a solo Pacific Ocean crossing. Estimations of sleep hours, state anxiety, and perceived fatigue were self-reported by the sailor on a daily basis using a specific questionnaire. The most important finding is that the sailor's deliberate sleep strategy, 5.4 h sleep per day (24% less than on-shore), was enough to keep his anxiety and perceived fatigue within acceptable limits and enabled him to achieve his goal, which was the first crossing of the Pacific Ocean on a catamaran of less than 6 m. In conclusion, our results suggest that the sailor observed in the present case study was able to minimize anxiety and perceived fatigue with adequate sleep to optimize his performance, security, and to achieve his goal.

Modelling the Relationships between Training, Anxiety, and Fatigue in Elite Athletes

This study investigated the effects of 40-week training on anxiety and perceived fatigue in four elite triathletes. Anxiety and perceived fatigue were self-reported by the subjects twice a week by the way of a specific questionnaire and were linked by a mathematical model to the training loads calculated from the exercise heart rate. A significant relationship (r=0.32; p<0.001) between the training loads and anxiety was identified using a two-component model: a first, negative (i.e., anxiety decreased) short-term (tau (1)=23 days) function and a second, positive long-term (tau (2)=59 days) function. The relationship between the training loads and perceived fatigue was significant (r=0.30; p<0.001), with one negative function (tau (1)=4 days). This mathematical model can potentially describe the relationships between training loads and anxiety or perceived fatigue and may improve both the adjustment of the duration of tapering and the early detection of staleness.

Effects of Hypoxic Interval Training on Cycling Performance

PURPOSE

The aim of this study was to test the hypothesis that intermittent hypoxic interval training improves sea level cycling performance more than equivalent training in hypoxia or normoxia.

METHODS

Thirty-three well-trained cyclists and triathletes (25.9 +/- 2.7 yr, VO(2max) 66.1 +/- 6.1 mL.min(-1).kg(-1)) were divided into three groups: intermittent hypoxic (IHT, N = 11, P(I)O(2) of 100 mm Hg), intermittent hypoxic interval training (IHIT, N = 11) and normoxia (Nor, N = 11, P(I)O(2) of 160 mm Hg) and completed a 7-wk training program, consisting of two high-intensity (100 or 90% relative peak power output) interval training sessions each week. Each interval training session was performed in a laboratory on the subject's own bicycle, in normoxic or hypoxic conditions for the Nor and the IHT group, respectively. The IHIT group performed warm-up and cool-down plus recovery from each interval in hypoxic conditions. In contrast to IHT, interval exercise bouts were performed in normoxic conditions.

RESULTS

Mean power output during a 10-min cycle time trial improved after the first 4 wk of training by 5.2 +/- 3.9, 3.7 +/- 5.9, and 5.0 +/- 3.4% for IHIT, IHT, and Nor, respectively, without significant differences between groups. Moreover, mean power output did not show any significant improvement in the following 3 wk in any group. VO(2max) (L.min(-1)) increased only in IHIT during the training period (8.7 +/- 9.1%; P < 0.05). No changes in cycling efficiency or in hematological variables (P > 0.05) were observed.

CONCLUSION

Four weeks of interval training induced an improvement in endurance performance. However, short-term exposure to hypoxia (approximately 114 min.wk(-1)) did not elicit a greater increase in performance or any hematological modifications.

Evaluation of a Theoretical Model to Quantify the Sources of Metabolic Cost in Walking

OBJECTIVE

To evaluate the validity of a theoretical model of walking in which the oxygen uptake (V(O2)) is described as a function of speed by an equation in the form y = ax + b, with constant a representing the metabolic cost for performing the walking movement, and constant b representing the sum of the metabolic costs for basal metabolism and maintaining balance and posture.

DESIGN

Repeated-measures analysis of variance was used to analyze our theoretical model. In a human exercise research laboratory, 12 healthy male subjects walked on a level treadmill at speeds of 0.39-1.83 m/sec under a control condition, while wearing "instability" shoes with peripheral vision obstructed, and with 2-kg weights around each wrist. Total transported mass was the same under each condition through the carriage of 4 kg in a back pack during the control and instability conditions. Outcome was determined by equations describing (V(O2)) as a function of speed and by kinematics of the center of mass.

RESULTS

The constant b was higher (P < 0.01) for the instability condition than the other conditions, but constant a did not differ among the conditions. However, external work was greatest (P < 0.05) for the instability condition.

CONCLUSIONS

Because the kinematic data demonstrate that the instability condition increased the metabolic cost for performing the walking movement compared with the control condition, and there was no difference among conditions in constant a, the theoretical model seems invalid.

Assessment of Wheelchair Drag Resistance Using a Coasting Deceleration Technique

OBJECTIVE

To apply a recently developed coasting deceleration method to measure rolling and aerodynamic resistances opposing wheelchair propulsion on a variety of different wheelchairs and wheel combinations and on two different ground surfaces.

DESIGN

For each condition, 20-25 trials were performed across a speed range of approximately 70-300 m/min. The least-squares method was then used to arrive at values for the coefficient of rolling resistance (CR) and effective frontal area of the wheelchair and occupant.

RESULTS

Wheelchair rolling resistance was found to be velocity dependent under some circumstances. CR values on linoleum differed among folding lightweight wheelchairs and when compared with a rigid ultralight and racing wheelchair. Changing rear wheels and tires on one wheelchair resulted in a 14% difference in CR. Carpet increased CR values by an average of 0.0118 over the values determined on linoleum. As expected, effective frontal area of the wheelchair and occupant values were lower for the racer than for the folding lightweight wheelchair.

CONCLUSIONS

Wheelchair rolling resistance is not always independent of velocity, and CR on linoleum can vary among wheelchairs by as much as seven-fold, and carpet can more than double CR.

Modelling the transfers of training effects on performance in elite triathletes

This study investigated the effects of 40-weeks training in swimming, cycling and running on performances in swimming, running and triathlon competitions in four elite triathletes. The training stimulus was calculated using the exercise heart rate. The level of performance was measured in running by a submaximal 30 min run, in swimming by a 5 x 400 m all-out test and subjectively in triathlon competitions. A mathematical model using one to three first order transfer functions linked actual and modelled performances by minimizing the residual sum of squares between them. The relationships between training and performances were significant in running (tau(1) = 20; tau(2) = 10; r = 0.74; p < 0.001) and in swimming (tau(1) = 31; r = 0.37; p = 0.03), supporting the principle of specificity of the training loads. Cross-transfer training effects were identified between cycling and running (tau(1 = )42; r = 0.56; p < 0.001), but not with swimming performances. In addition, the training loads completed in running were shown to have a major effect on performances in triathlon competition (tau(1 = )52; tau(2 = )4; r = 0.52; p < 0.001), indicating that running training is an essential part of triathlon performance. Swimming appears to be a highly specific activity, which does not gain nor provide benefits from/to other activities (i. e. cycling and running). The present study shows that cross-transfer training effects occur between cycling training and running performance in elite triathletes. A similar cross-training effect does not seem to occur for swimming performance.

Duration and seriousness of running mechanics alterations after maximal cycling in triathletes. Influence of the performance level

BACKGROUND

Non-experienced triathletes use to complain about the difficulty to run after cycling. We tested the hypothesis that elite triathletes have lower and/or shorter alterations in running mechanics following a maximal cycling exercise than their less efficient counterparts.

METHODS

The mechanical alterations in running after exhaustive cycling exercise were studied in eight elite (E) and 18 middle-level (M) triathletes. Before and after maximal cycling exercise, the subjects completed two 7-min runs on a treadmill at a velocity corresponding to that sustained during a triathlon. External mechanical cost was quantified during the first and last minute of each run from displacements of the centre of mass using a kinematic arm.

RESULTS

The effect of cycling on the potential, kinetic and mechanical costs (respectively, 7.1+/-6.0% and 0.4+/-6.9% increase for M and E) during the first minute of running appeared to be more adverse (p<0.05) for M than E. The mechanical changes between pre- and postcycling exercise were similar among the two groups at the 6th minute, suggesting that the mechanical alterations due to a cycling fatigue in M are brief.

CONCLUSIONS

Since the needs to run efficiently immediately after cycling are associated with performance in triathlon, the results of the present study have practical implications for training.

Alterations in running economy and mechanics after maximal cycling in triathletes: influence of performance level

The effects of the triathlon performance level on the metabolic and mechanical alterations in running after an exhaustive cycling exercise were studied. Eight elite and 18 middle-level triathletes completed two 7 min runs on a treadmill at a velocity corresponding to that sustained during a triathlon before and after maximal cycling exercise. Energy cost of running was quantified during the last minute of each run from the net oxygen uptake. External mechanical cost was quantified during the last minute of each run from displacements of the centre of mass using a kinematic arm. The effect of cycling on the running energy cost differed when comparing the elite (from 4.01+/-0.46 to 3.86+/-0.34J x kg(-1) x m(-1)) and the middle-level triathletes (from 3.67+/-0.37 to 3.76+/-0.39 x kg(-1) x m(-1) (P<0.01). The effect of cycling on the respiratory muscle O2 was more important (P<0.05) for the middle-level (from 120.1+/-27.2 to 166.4+/-47.8 ml x min(-1)) than for elite triathletes (from 124.5 +/- 24.5 to 143.7 +/- 28.9 ml x min(-1)). A tendency to a decrease of the mechanical cost and of the vertical displacement of the centre of mass during the braking phase was observed for the elite triathletes, suggesting a better leg stiffness regulation than for their less successful counterparts.

Simplified deceleration method for assessment of resistive forces in cycling

PURPOSE

The purpose of this study was to develop and test a simplified deceleration technique for measurement of aerodynamic and rolling resistances in cycling.

METHODS

Coast-down tests were performed in level hallways with an experienced cyclist as the rider. Average initial velocities were 2.5-12.8 m x s(-1)) The deceleration technique was simplified by the use on only three switches and a derivation that did not require an assumption that deceleration is constant. The effective frontal area (AC(D)) and coefficient of rolling resistance (CR) were then calculated through a derivation from the equation for resistive forces opposing motion. Method reproducibility was tested by comparison of results for four tests of 30 trials under identical conditions. Method sensitivity was tested by performing 30 trials with three different rider head positions and four different transported mass conditions.

RESULTS

Analysis of variance revealed that there were no differences among the results in the reproducibility study for either AC(D) or C(R). Furthermore, the reproducibility tests revealed mean errors of only 0.66% and 0.70% for AC(D) and CR, respectively. ANOVA identified a significant increase (P < 0.001) in rolling resistance with external loading and a significant effect (P < 0.001) of head position on AC(D). Mean (+/-SD) values for AC(D) and C(R) from tests in a racing aeroposture with the head up, the head in line with the trunk, and the head in an intermediate position were 0.304 +/- 0.011, 0.268 +/- 0.010, and 0.262 +/- 0.013 m2, respectively. C(R) averaged 0.00368 in the three head positions.

CONCLUSIONS

The findings indicate that this simplified deceleration technique is satisfactorily reproducible and sensitive for measurement of aerodynamic and rolling resistances in cycling.

Poling forces during roller skiing: effects of technique and speed

PURPOSE

Although it has been reported that the majority of propulsive forces are generated through the poles with ski skating, no study has systematically examined poling forces among different skating techniques. The objective of the present study was to examine poling forces and timing during roller skiing on a 2.1% uphill.

METHODS

Nine highly skilled cross-country skiers roller skied at three paced speeds and maximal speed using the V1 skate (V1), V2-alternate (V2A), V2 skate (V2), and double pole (DP) techniques while poling forces and timing were measured with piezoelectric transducers.

RESULTS

Peak force (PF) values with the skating techniques were significantly lower than with DP and ranged from 18.9 +/- 3.1% of body weight (BW) to 31.5 +/- 5.6% BW across the speeds of the study. Average force over the entire cycle (ACF) increased with speed with DP, V2A and V1 (P < 0.01) but not with V2. PF and ACF were higher (P < 0.01) with V2 than V1 and V2A. Poling time was longer (P < 0.01) with V2A compared with V1 and V2.

CONCLUSIONS

The results of this study suggest that 1) the use of the upper body is greater with V2 than with other skating techniques while there is a relatively greater reliance on the lower body for generation of the additional propulsive forces required to increase velocity, and (2) poling forces do not appear to be as effectively applied with V2 as with V2A.

Poling forces during roller skiing: effects of grade

PURPOSE

A substantial proportion of the propulsive forces required for uphill skiing are generated from the upper body, but no study has systematically examined poling forces at different slopes. In the present experiment, poling forces and timing were examined during roller skiing on 2.1% and 5.1% uphills.

METHODS

Nine highly skilled cross-country skiers roller skied at paced submaximal and at maximal speeds using the V1 skate (V1) and double pole (DP) techniques. Poling forces and timing were measured with piezoelectric transducers.

RESULTS

Peak force (PF), average force (AF) and average force over the entire cycle (ACF) were significantly greater (P < 0.01) at the steeper grade with both techniques. Values for the ratio of V1 to DP did not differ between the two grades for PF, AF, and ACF but tended to increase with velocity for both techniques. With both V1 and DP, upper body recovery time was shorter (P < 0.01) at the steeper grade, and cycle rate was greater (P < 0.01) at the steeper grade.

CONCLUSIONS

We conclude that 1) the relative demands on the upper body with V1 compared with DP were similar between the two grades, and 2) the responses to an elevation in grade of increased poling forces, shortened poling recovery times, and increased cycle rate are comparable to the responses to an increase in speed.

Cycle rate variations in roller ski skating: effects on oxygen uptake and poling forces

The purpose of this study was to examine the effect of cycle rate (CR) variations on the metabolic cost and upper body forces during roller skiing with the V2-alternate technique on flat terrain. Nine highly skilled cross-country skiers roller skied at a paced speed of 18.0+/-0.1 km x h(-1) using their chosen CR, and CRs that were 10% slower and 20% faster. Oxygen uptake (VO2) was determined through collection of expired gases into a meterological balloon and poling forces were measured with piezoelectric transducers during the last 30 s of each four minute trial of roller skiing. One-way repeated measures ANOVA revealed that VO2 varied significantly with CR (p=0.02) with the chosen CR being significantly lower than the higher CR (p < 0.05). Poling forces and poling time were not significantly different among the CR conditions. The present results demonstrate that 1) an alteration in cycle rate affects metabolic cost of roller ski skating, 2) skiers tend to naturally select the most economical cycle rate, and 3) moderate variations in cycle rate do not appear to affect propulsive force generation through the poles in roller skiing.

Effect of rolling resistance on poling forces and metabolic demands of roller skiing

OBJECTIVE

To examine the effect of an increase in roller ski rolling resistance on the physiological and upper body demands of roller skiing with the V2-alternate technique.

METHODS

Nine highly skilled cross-country skiers roller skied at three paced speeds on a flat oval loop using roller skis with high (HiR) and low (LowR) rolling resistance. Oxygen uptake (VO2), heart rate, and poling forces were measured during the last 30 s and rating of perceived exertion (RPE) was requested immediately after each 4-min bout of roller skiing.

RESULTS

VO2 and all force-related variables increased significantly with speed and were higher (P < 0.01) for HiR at given speeds. Poling time was similar between HiR and LowR, whereas poling recovery time was shorter (P = 0.0002) and cycle rate was higher (P = 0.002) for HiR. For given VO2 levels, peak and average forces, heart rates, and RPE values were similar between HiR and LowR, whereas average poling force across the cycle was greater (P = 0.006) and duty cycle (i.e., percentage of cycle when poling forces were applied) was higher (P = 0.0001) with HiR.

CONCLUSIONS

1) The decrease in poling recovery time and increase in cycle rate associated with an increase in roller ski rolling resistance is comparable to the effect previously observed from increasing grade and probably occurs as a means of limiting deceleration. 2) Since changes in rolling resistance do not alter the relationships of RPE and heart rate with VO2, the central cardiovascular adaptations from roller ski training should not be affected by the rolling resistance of the roller skis. 3) Higher resistance roller skis are likely to induce greater upper body aerobic adaptations than lower resistance roller skis.