Climatic heat stress and performance in the Wingate Anaerobic Test

Development and Validation of Prediction Formula of Wingate Test Peak Power From Force-Velocity Test in Male Soccer Players

Peak power of the Wingate anaerobic test (WAnT), either in W (Ppeak) or in W.kg^–1 (rPpeak), has been widely used to evaluate the performance of soccer players; however, its relationship with force–velocity (F-v) test (e.g., whether these tests can be used interchangeably) has received little scientific attention so far. The aim of this work was to develop and validate a prediction equation of Ppeak and rPpeak from F-v characteristics in male soccer players. Participants were 158 adult male soccer players (sport experience 11.4 ± 4.5 years, mean ± standard deviation, approximately five weekly training units, age 22.6 ± 3.9 years, body mass 74.8 ± 7.8 kg, and height 178.3 ± 7.8 cm) who performed both WAnT and F-v test. An experimental (EXP, n = 79) and a control group (CON, n = 79) were used for development and validation, respectively, of the prediction equation of Ppeak and rPpeak from F-v test. In EXP, Ppeak correlated very largely with body mass (r = 0.787), fat-free mass (r = 0.765), largely with maximal power of F-v test (P_max; r = 0.639), body mass index (r = 0.603), height (r = 0.558), moderately with theoretical maximal force (F₀; r = 0.481), percentage of body fat (r = 0.471), fat mass (r = 0.443, p < 0.001); rPpeak correlated with rPmax (largely; r = 0.596, p < 0.001), theoretical maximal velocity (v₀; moderately; r = 0.341, p = 0.002), F₀ (small magnitude; r = 0.280, p = 0.012), BF (r = −0.230, p = 0.042), and fat mass (r = −0.242, p = 0.032). Ppeak in EXP could be predicted using the formula “44.251 + 7.431 × body mass (kg) + 0.576 × P_max (W) – 19.512 × F₀” (R = 0.912, R² = 0.833, standard error of estimate (SEE) = 42.616), and rPpeak from “3.148 + 0.218 × rPmax (W.kg^–1) + v0 (rpm)” (R = 0.765, R² = 0.585, SEE = 0.514). Applying these formulas in CON, no bias was observed between the actual and the predicted Ppeak (mean difference 2.5 ± 49.8 W; 95% CI, −8.7, 13.6; p = 0.661) and rPpeak (mean difference 0.05 ± 0.71 W.kg^–1; 95% CI, −0.11, 0.21, p = 0.525). These findings provided indirect estimates of Ppeak of the WAnT, especially useful in periods when this test should not be applied considering the fatigue it causes; in this context, the F-v test can be considered as an alternative of exercise testing for estimating the average Ppeak of a group of soccer players rather than for predicting individual scores when the interindividual variation of performance is small.

Combined sprint and resistance training abrogates age differences in somatotropic hormones

The aim of this investigation was to compare serum growth hormone (GH), insulin-like growth factor-1 (IGF-1) and insulin-like growth factor-binding protein-3 (IGFBP-3) in response to a combined sprint and resistance training (CSRT) program in young and middle-aged men.Thirty-eight healthy, moderately trained men participated in this study. Young and middle-aged men were randomly assigned to, a young training group (YT = 10, 21.4±1.2yrs) ora young control group (YC = 9, 21.6±1.8 yrs), a middle-aged training group (MAT = 10, 40.4±2.1 yrs) or a middle-aged control group (MAC = 9, 40.5±1.8 yrs). Participants performed the Wingate Anaerobic Test (WAnT) before and after a 13-week CSRT program (three sessions per week). Blood samples were collected at rest, after warm-up, immediately post-WAnT, and 10 min post-WAnT. CSRT induced increases in GH at rest and in response to the WAnT in YT and MAT (P<0.05). CSRT-induced increases were observed for IGF-1 and IGFBP-3 at rest in MAT only (P<0.05). Pre-training, GH, IGF-1 and IGFBP-3 were significantly higher at rest and in response to the WAnT in young participants as compared to their middle-aged counterparts (P<0.05). Post-training, YT and MAT had comparable basal GH (P>0.05). In response to the WAnT, amelioration of the age-effect was observed between YT and MAT for IGF-1 and IGF-1/IGFBP-3 ratio following CSRT (P>0.05). These data suggest that CSRT increases the activity of the GH/IGF-1 axis at rest and in response to the WAnT in young and middle-aged men. In addition, CSRT reduces the normal age-related decline of somatotropic hormones in middle-age men.

Myocardial functional responses do not contribute to maximal exercise performance in the heat

BACKGROUND

Both the extent and means by which maximal oxygen uptake ([Formula: see text]) is depressed by elevated ambient temperature are uncertain. Particularly, information is currently unavailable regarding the possible influence of alterations in myocardial function on [Formula: see text] and performance during exercise in the heat. This study investigated the effects of environmental heat on [Formula: see text], peak work capacity, and myocardial function during a standard, progressive cycle test to exhaustion. Twelve euhydrated men (aged 20.7 ± 1.7 years) performed a maximal cycle test in an environmental chamber in both heat stress [35°C, 30% relative humidity (RH)] and temperate (20°C, 30% RH) conditions with measurement of standard gas exchange variables, core temperature, and echocardiographic measures of cardiac function.

RESULTS

A small but statistically significant reduction of peak work capacity was observed in the heat stress versus temperate conditions (253 ± 30 and 259 ± 30 W, respectively, p = 0.02). Mean [Formula: see text] was not statistically different in the two conditions (p = 0.16) but values were 3.4% lower in the heat, and 9 of 12 participants demonstrated lower values in the heat stress trial. No differences in responses of heart rate, cardiac output, stroke volume, core temperature, hydration status, or myocardial systolic or diastolic function were observed between the two conditions, but perceived body temperature was higher in the heat.

CONCLUSIONS

The small, negative impact of heat on exercise performance and [Formula: see text] could not be explained by disturbances in myocardial functional responses to exercise in young adult males.

The measurement of maximal (anaerobic) power output on a cycle ergometer: a critical review

The interests and limits of the different methods and protocols of maximal (anaerobic) power (Pmax) assessment are reviewed: single all-out tests versus force-velocity tests, isokinetic ergometers versus friction-loaded ergometers, measure of Pmax during the acceleration phase or at peak velocity. The effects of training, athletic practice, diet and pharmacological substances upon the production of maximal mechanical power are not discussed in this review mainly focused on the technical (ergometer, crank length, toe clips), methodological (protocols) and biological factors (muscle volume, muscle fiber type, age, gender, growth, temperature, chronobiology and fatigue) limiting Pmax in cycling. Although the validity of the Wingate test is questionable, a large part of the review is dedicated to this test which is currently the all-out cycling test the most often used. The biomechanical characteristics specific of maximal and high speed cycling, the bioenergetics of the all-out cycling exercises and the influence of biochemical factors (acidosis and alkalosis, phosphate ions…) are recalled at the beginning of the paper. The basic knowledge concerning the consequences of the force-velocity relationship upon power output, the biomechanics of sub-maximal cycling exercises and the study on the force-velocity relationship in cycling by Dickinson in 1928 are presented in Appendices.

Temperature and neuromuscular function

This review focuses on the effects of different environmental temperatures on the neuromuscular system. During short duration exercise, performance improves from 2% to 5% with a 1 °C increase in muscle temperature. However, if central temperature increases (i.e., hyperthermia), this positive relation ceases and performance becomes impaired. Performance impairments in both cold and hot environment are related to a modification in neural drive due to protective adaptations, central and peripheral failures. This review highlights, to some extent, the different effects of hot and cold environments on the supraspinal, spinal and peripheral components of the neural drive involved in the up- and down-regulation of neuromuscular function and shows that temperature also affects the neural drive transmission to the muscle and the excitation-contraction coupling.

Acute heat exposure increases high-intensity performance during sprint cycle exercise

The purpose of this study was to investigate the effects of acute heat exposure at thermal balance on high-intensity performance during sprint cycle exercise. Nine healthy male subjects were tested in three different, well-controlled environments in an environmental chamber: T (22 degrees C, 65% RH), H1 (30 degrees C, 55% RH) and H2 (35 degrees C, 62% RH), each test being carried out on a different day following a randomized sequence. After 30 min of exposure to the set environment, subjects performed the 30-s sprint cycle exercise. Heart rate, rectal and skin temperatures were measured prior to exercise, at rest, before and after environmental exposure, and after exercise. There were no differences in subjects' core temperature or heart rate prior to exercise. However, skin temperature was significantly higher in hot trials compared with the control throughout the experimental session (P < 0.05). Peak power was significantly higher in the hot environments compared with the control. Mean power was higher only in H2 compared with T (P < 0.05). This difference in power output was the consequence of a faster pedaling cadence in the hot trials (P < 0.05). Plasma ammonia was higher in the hot trials versus control at 4 min post-sprint. No differences in blood lactate levels at 3 min post-sprint were observed between tests. The results of this study suggest that the exposure to hot environment caused an improvement in power output for a single 30-s sprint. This increase in power output was associated with an elevation in plasma ammonia suggestive of an increase in adenine nucleotide loss.

Reliability of performance in repeated sprint cycling tests

We have estimated the reliability of performance in a commonly employed exercise test consisting of repeated sprints on a cycle ergometer. Eight recreationally active young men completed a practice trial and three more trials at 3- to 6-day intervals. Each trial consisted of two bouts of 30-s maximal-effort cycling on an electromagnetically braked cycle ergometer; the bouts were separated by 4 min of rest. The typical (standard) errors of measurement for peak and mean power between trials 2 to 4 were 2.5 and 1.7% respectively for the first bout and 1.9 and 1.8% for the second bout. These errors are substantially less than those in previous reliability studies of single 30-s sprint tests, probably because of differences in quality of ergometer. The typical errors for the difference between bouts (i.e., fatigue) for peak power and mean power were 3.0 and 2.5%, respectively. Typical errors for the average of the two bouts were 1.6 and 1.2% for peak and mean power respectively, which are small enough to give adequate precision for moderate treatment effects in studies with modest sample sizes.

Intermittent running: muscle metabolism in the heat and effect of hypohydration

PURPOSE

This study reports two studies that investigated the reason for a poorer intermittent supramaximal running performance previously found in the heat (Maxwell et al., The effect of climatic heat stress on intermittent supramaximal running performance in humans. Exp. Physiol. 81:833-845, 1996). The first study tested the hypothesis that it was due to different rates of substrate metabolism. The second study tested whether a greater level of hypohydration led to an earlier exhaustion time.

METHODS

A maximal anaerobic running test (MART) was the exercise model used. This involved repeated 20-s runs, each at increasing intensities, with 100 s of passive recovery between runs.

RESULTS

In study 1, eight male subjects performed the MART on two occasions at either 32.8+/-0.3 degrees C, 80.5+/-1.6% relative humidity (RH), or 21.3+/-0.4 degrees C, 48.8+/-2.2% RH. Needle biopsy samples were taken from the vastus lateralis muscle before and immediately after the MART. In study 2, 11 male subjects performed the MART in a moderately hypohydrated (HYPO) and euhydrated (EUH) state while in a cool environment. In study 1, performance was significantly worse in the hot compared with the cool environment (138+/-7 vs. 150+/-6 s, respectively, P<0.05). No differences were observed in the change in muscle glycogen (100.3+/-15.1 vs. 107.0+/-15.6 mmol glucosyl units x kg dry muscle(-1)) or muscle lactate (102.9+/-18.2 vs. 100.5+/-16.6 mmol x kg dry muscle(-1)) between the hot and cool environments, respectively. In study 2, performance was worse in the HYPO (148+/-9 s) compared with the EUH (154+/-9 s) trial (P<0.05).

CONCLUSIONS

These results indicate that a reduced intermittent supramaximal running performance in the heat is not caused by greater muscle glycogenolysis or lactate accumulation. Further, a poorer intermittent sprinting performance is experienced in a hypohydrated compared with a euhydrated state.

Reliability of tests to determine peak aerobic power, anaerobic power and isokinetic muscle strength in children with spastic cerebral palsy

Test-retest reliability of measurements of peak aerobic power (cycle ergometer), anaerobic power (cycle ergometer), and isokinetic muscle strength of the knee (Cybex) was established in 12 young children with cerebral palsy (spastic diplegia/tetraplegia; mean age 8.8 years) and in addition in 39 healthy controls (mean age 9.2 years). The cycle ergometer tests were found to be reliable in both the group with CP and the control group (test-retest correlations varying from 0.72 to 0.96). The isokinetic strength test in the group with CP was only reliable at 30 degrees/s, whereas in the control group high test-retest correlations were also found at 60 degrees/s and 120 degrees/s.

The effect of normocapnic hypoxia and the duration of exposure to hypoxia on supramaximal exercise performance

Two investigations were designed that (a) evaluated the effect of the respiratory alkalosis that accompanies breathing an hypoxic (H) gas mixture and (b) examined the influence of the duration of breathing this H mixture on the subsequent performance of 45 s supramaximal dynamic exercise. In experiment 1, 12 men performed a 45-s Wingate Test (WT) on three occasions breathing a normoxic (N; 20.9% O2), H (11.3% O2), or normocapnic hypoxic (H+CO2; 11.5% O2, 2.25% CO2) gas mixture for 20 min prior to performing the WT. For experiment 2, nine men performed a 20-min normoxic (N20) and three hypoxic WT trials which consisted of breathing an 11% O2 balance N2 gas mixture for 10 min (H10), 20 min (H20) or 30 min (H30) prior to the WT. For experiment 1, VO2 was significantly reduced during the 45-s H [mean (SD); 1.22 (0.23) l] and H+CO2 [1.12 (0.18) l] trials compared with the N trial [1.78 (0.18) l] Peak power output (Wpeak) during WT was similar across trials. However, a small (less than 3%) but significant reduction in the mean power output (W) was observed in both the H and H+CO2 trials [6.8 (0.6) W.kg-1] compared with the N trial [7.0 (0.6) W.kg-1]. Prior to performing the WT, blood pH and PCO2 were similar [7.40 (0.02) and 5.3 (0.3) kPa, respectively] for the N and H+CO2 trials. A respiratory alkalosis accompanied the H condition [7.46 (0.02) for pH and 4.6 (0.3) kPa for PCO2.(ABSTRACT TRUNCATED AT 250 WORDS)

Current concepts in the rehabilitation of the injured athlete

A comprehensive approach to the rehabilitation of injured athletes necessitates that an injury be treated specifically with appropriate measures to achieve comfort and that early prescription of various exercises be designed to promote optimal healing and a return to function. In addition, the athlete must be assisted to regain and maintain a proper fitness level before returning to a sport. Finally, the prevention of athletic injuries becomes an ongoing concern that necessitates monitoring and education of those involved in sports activities.

Load optimization for the Wingate Anaerobic Test

The purpose of the present study was to define the optimal loads (OL) for eliciting maximal power-outputs (PO) in the leg and arm modes of the 30s Wingate Anaerobic Test (WAnT). Eighteen female and seventeen male physical education students, respectively 20.6 +/- 1.6 and 24.1 +/- 2.5 years old, volunteered to participate. In each of the total five sessions, the test was administered twice on a convertible, mechanically braked cycle-ergometer, once for the legs and once for the arms. The five randomized, evenly-spaced resistance loads ranged from 2.43 to 5.39 Joule per pedal revolution per kg body weight (B. W.) for the legs, and from 1.96 to 3.92 for the arms. The measured variables were mean (MP x kg-1) and peak PO as well as absolute and relative measures of fatigue. A parabola-fitting technique was employed to define the optimal loads from the MP x kg-1 data. The resulting OL were 5.04 and 5.13 Joule x Rev-1 x kg B.W.-1 in the leg and 2.82 and 3.52 in the arm tests for the women and men, respectively. OL were shown to depend on PO magnitude. However, within a two-load span (0.98 Joule x Rev-1 x kg B.W.-1) about the OL, MP x kg-1 did not vary by more than 1.4% in the leg and 2.2% in the arm tests. It is suggested that although the WAnT is rather insensitive to moderate variation in load assignment, improved results could be obtained by using the stated OL as guidelines that may be modified according to individual body build, composition, and, particularly, anaerobic fitness level.