Dale W. Chapman

Comparison of responses to strenuous eccentric exercise of the elbow flexors between resistance-trained and untrained men

This study compared resistance-trained and untrained men for changes in commonly used indirect markers of muscle damage after maximal voluntary eccentric exercise of the elbow flexors. Fifteen trained men (28.2 ± 1.9 years, 175.0 ± 1.6 cm, and 77.6 ± 1.9 kg) who had resistance trained for at least 3 sessions per week incorporating exercises involving the elbow flexor musculature for an average of 7.7 ± 1.4 years, and 15 untrained men (30.0 ± 1.5 years, 169.8 ± 7.4 cm, and 79.9 ± 4.4 kg) who had not performed any resistance training for at least 1 year, were recruited for this study. All subjects performed 10 sets of 6 maximal voluntary eccentric actions of the elbow flexors of one arm against the lever arm of an isokinetic dynamometer moving at a constant velocity of 90°·s−1. Changes in maximal voluntary isometric and isokinetic torque, range of motion, upper arm circumference, plasma creatine kinase activity, and muscle soreness before, immediately after, and for 5 days after exercise were compared between groups. The trained group showed significantly (P < 0.05) smaller changes in all of the measures except for muscle soreness and faster recovery of muscle function compared with the untrained group. For example, muscle strength of the trained group recovered to the baseline by 3 days after exercise, where the untrained group showed approximately 40% lower strength than baseline. These results suggest that resistance-trained men are less susceptible to muscle damage induced by maximal eccentric exercise than untrained subjects.

Partial protection against muscle damage by eccentric actions at short muscle lengths

PURPOSE This study investigated the hypothesis that maximal eccentric actions at a short muscle length would fail to confer a protective effect against muscle damage induced by maximal eccentric exercise at a long muscle length. METHODS Eleven males performed 24 maximal eccentric actions of the nondominant elbow flexors over a short extension range from an elbow joint angle of 0.87-1.74 rad (S-ECC) followed 4 wk later by eccentric actions at a long range of 2.27-3.14 rad (L-ECC). A second group of 11 males performed L-ECC on two occasions using the nondominant arm separated by 4 wk. Changes in maximal isometric strength, range of motion, upper arm circumference, muscle soreness, plasma creatine kinase and aspartate aminotransferase activities, and B-mode ultrasound images were compared between bouts and between groups by two-way repeated measures ANOVA. RESULTS All measures changed significantly (P < 0.01) after the first bout; however, the effects were significantly (P < 0.01) smaller after S-ECC compared with L-ECC. The second bout resulted in significantly (P < 0.01) reduced changes in all measures compared with the first bout in the subjects who performed L-ECC on both occasions. The subjects who performed S-ECC in the first bout displayed significantly smaller changes after L-ECC than those seen after L-ECC alone, with the degree of attenuation being around 50-70%. CONCLUSION Contrary to the hypothesis, S-ECC provided partial but effective protection against L-ECC. This result suggests adaptations associated with the repeated bout effect were also produced after S-ECC, but the degree of adaptations was not as strong as that by L-ECC. Eccentric exercise at a short extension range can be used as a strategy to present severe muscle damage.

TWELVE-MONTH TRAINING-INDUCED CHANGES IN ELITE INTERNATIONAL VOLLEYBALL PLAYERS

Sheppard, JM, Chapman, DW, Gough, C, McGuigan MR, and Newton, RU. Twelve-month training-induced changes in elite international volleyball players. J Strength Cond Res 23(7): 2096-2101, 2009-The purpose of this investigation was to examine the strength, power, and anthropometric contributors to vertical jump performances that are considered specific to volleyball success, including countermovement vertical jump (CMVJ) and spike jump (SPJ), by examining changes across 12 months in elite volleyball players. Anthropometry (height, mass, ∑7 skinfolds), vertical jump ability (CMVJ, SPJ, and depth jumps from 35 cm), kinetic and kinematic data from an unloaded and loaded (body mass + 50%) jump squat were assessed before and after 12 months of training in 20 elite male volleyball players. To examine the association between the change in each of the strength, power, and anthropometric variables with the changes in CMVJ and SPJ, a correlation analysis of the percent change of each variable with the percent change in CMVJ and SPJ was performed. A significant correlation (r = 0.47; p = 0.04) was observed between changes in CMVJ and SPJ. Significant (p = 0.006-0.02) improvements in CMVJ were associated with increased peak force in the unloaded (r = 0.61) and loaded jump squat (r = 0.59) and greater relative power and peak velocity in the loaded jump squat (r = 0.49 and 0.51, respectively). The significant increase in CMVJ was strongly associated (r = 0.865; p < 0.001) with an improved depth-jump ability. Significant (p = 0.003-0.03) increases in SPJ were related to increases in relative power (r = 0.64), peak force (r = 0.46), and peak velocity (r = 0.49) in the loaded jump and improved depth-jumping ability (r = 0.591). This study demonstrates that, in an elite population of volleyball players, stretch-shortening cycle performance and the ability to tolerate high stretch loads, as in the depth jump, are critical to improving jumping performance.

Effect of Lengthening Contraction Velocity on Muscle Damage of the Elbow Flexors

PURPOSE This study investigated the effect of lengthening contraction velocity on exercise-induced muscle damage. METHODS Sixteen men were placed into two groups performing either 30 (N = 8) or 210 (N = 8) maximal lengthening contractions of the elbow flexors on an isokinetic dynamometer. Dominant and nondominant arms were randomly assigned for a slow-velocity (S: 30 degrees.s(-1)) or a fast-velocity (F: 210 degrees.s(-1)) exercise separated by 14 d. Maximal voluntary strength of isometric contractions (iMVC) and isokinetic concentric contractions (cMVC), range of motion (ROM), upper-arm circumference, muscle soreness, and serum creatine kinase (CK) activity were measured before, immediately after, and 1-120 h after exercise. Changes in these measures over time were compared by a two-way repeated-measures ANOVA to examine the effect of velocity in the same number of contractions (S30 vs F30; S210 vs F210) or the effect of contraction number at the same velocity (S30 vs S210; F30 vs F210). RESULTS A significant (P < 0.05) interaction effect was evident only for iMVC between S30 and F30, but it was evident for iMVC, cMVC, ROM, and CK between S210 and F210. Changes in most of the measures were significantly (P < 0.05) smaller after 30 contractions (S30 and F30) than after 210 contractions (S210 and F210). CONCLUSION These results suggest that the effect of contraction velocity on the magnitude of muscle damage after 30 contractions is minor; however, when 210 lengthening contractions were performed, the effect of contraction velocity became conspicuous. It is concluded that fast-velocity lengthening contractions are likely to induce greater muscle damage than slow-velocity contractions; however, muscle fatigue seems to be a confounding factor for the velocity effect.

The Effect of Training with Accentuated Eccentric Load Counter-Movement Jumps on Strength and Power Characteristics of High-Performance Volleyball Players

The purpose of this study was to evaluate the training effects of using accentuated eccentric load counter-movement jumps on lower-body power characteristics in high-performance volleyball players. Sixteen volleyball players training full time with the state high-performance team participated in this 5 week training study. Prior to and at the completion of the study, jump squat testing with a lightweight (350 g) bar was conducted to determine kinetic and kinematic values for the lower body. Players were divided into either the accentuated eccentric load counter-movement jump group (AEJ) or normal (body-mass) counter-movement jump group (BMJ). The increases in displacement, velocity, and power values observed in the AEJ group were superior to those of the BMJ (p = 0.001–0.05, d = 1.06–1.97). The results of this study indicate that training with additional load during the eccentric phase of a counter-movement jump yields superior jump squat performance in comparison to typical counter-movement jump training in volleyball players who are already performing a high volume of jumping.

Work and peak torque during eccentric exercise do not predict changes in markers of muscle damage

Objectives: Large inter-subject variability in responses to eccentric exercise has been reported. This study investigated the hypothesis that the variability of changes in indirect markers of exercise-induced muscle damage (EIMD) would be explained by work performed and/or torque generated during eccentric exercise. Methods: Subjects (n = 53) performed 60 maximal eccentric actions of the elbow flexors on an isokinetic dynamometer that forcibly extended the elbow joint from 60° to 180° at a constant velocity (90° s−1). Markers of EIMD included maximal voluntary isometric contraction torque at 90° elbow flexion (MVC), range of motion, plasma creatine kinase activity and muscle soreness. Measurements were taken 2 days before, immediately after and 1–4 days post-exercise. Pearson’s correlation coefficient was used to examine relationships between exercise parameters (total work, change in total work, torque produced during exercise, change in peak torque) and markers of EIMD. Results: Large inter-subject variability was evident for both work and torque during exercise, and changes in all markers of EIMD. Contrary to the hypothesis, total work (normalised for individual pre-exercise MVC) did not correlate significantly with any markers of EIMD, with the exception of MVC (r = 0.3). Total work performed and changes in total work showed higher correlations with some markers, but no r-values exceeded 0.4. Normalised exercise torque and the changes in peak torque during exercise were not correlated with changes in MVC, or other markers. Conclusion: These results suggest the large inter-subject variability in responses to eccentric exercise is not associated with work performed or torque generated during eccentric exercise.

The Effect of Assisted Jumping on Vertical Jump Height in High-Performance Volleyball Players

Assisted jumping may be useful in training higher concentric movement speed in jumping, thereby potentially increasing the jumping abilities of athletes. The purpose of this study was to evaluate the effects of assisted jump training on counter-movement vertical jump (CMVJ) and spike jump (SPJ) ability in a group of elite male volleyball players. Seven junior national team volleyball players (18.0±1.0 yrs, 200.4±6.7 cm, and 84.0±7.2 kg) participated in this within-subjects cross-over counter-balanced training study. Assisted training involved 3 sessions per week of CMVJ training with 10 kg of assistance, applied through use of a bungee system, whilst normal jump training involved equated volume of unassisted counter-movement vertical jumps. Training periods were 5 weeks duration, with a 3-week wash-out separating them. Prior to and at the conclusion of each training period jump testing for CMVJ and SPJ height was conducted. Assisted jump training resulted in gains of 2.7±0.7 cm (p<0.01, ES=0.21) and 4.6±2.6 cm (p<0.01, ES=0.32) for the CMVJ and SPJ respectively, whilst normal jump training did not result in significant gains for either CMVJ or SPJ (p=0.09 and p=0.51 respectively). The changes associated with normal jump training and assisted jump training revealed significant differences in both CMVJ and SPJ (p=<0.03) in favour of the assisted jump condition, with large effect (CMVJ, ES=1.22; SPJ, ES=1.31). Assisted jumping may promote the leg extensor musculature to undergo a more rapid rate of shortening, and chronic exposure appears to improve jumping ability.

Association Between Anthropometry and Upper-Body Strength Qualities With Sprint Paddling Performance in Competitive Wave Surfers

Abstract Sheppard, JM, McNamara, P, Osborne, M, Andrews, M, Oliveira Borges, T, Walshe, P, and Chapman, DW. Association between anthropometry and upper-body strength qualities with sprint paddling performance in competitive wave surfers. J Strength Cond Res 26(12): 3345–3348, 2012—This study aimed to evaluate the potential association with anthropometry and upper-body pulling strength with sprint kinematics of competitive surfers. Ten competitive male surfers (23.9 ± 6.8 years, 177.0 ± 6.5 cm, 72.2 ± 2.4 kg) were assessed for stature, mass, arm span, ∑ 7 site skinfold thickness, pronated pull-up strength, and sprint paddling performance from a stationary start to 15 m. Pearson correlation analysis, and independent t-tests were used to compare potential differences between the slower and faster group of sprint paddlers. Strong associations were found between relative (total kilograms lifted per athlete mass) upper-body pulling strength and sprint paddling time to 5, 10, and 15 m, and peak sprint paddling velocity (r = 0.94, 0.93, 0.88, 0.66, respectively, p < 0.05) and relative upper-body pulling strength was found to be superior (p < 0.05) in the faster group, with large effect (d = 1.88). The results of this study demonstrate a strong association between relative upper-body pulling strength and sprint paddling ability in surfers. Strength and conditioning coaches working with competitive surfers should implement strength training with surfers, including an emphasis on developing relative strength, because this may have a strong influence on sprint paddling performance.

Identification of Cross-Country Skiing Movement Patterns Using Micro-Sensors

This study investigated the potential of micro-sensors for use in the identification of the main movement patterns used in cross-country skiing. Data were collected from four elite international and four Australian athletes in Europe and in Australia using a MinimaxX™ unit containing accelerometer, gyroscope and GPS sensors. Athletes performed four skating techniques and three classical techniques on snow at moderate velocity. Data from a single micro-sensor unit positioned in the centre of the upper back was sufficient to visually identify cyclical movement patterns for each technique. The general patterns for each technique were identified clearly across all athletes while at the same time distinctive characteristics for individual athletes were observed. Differences in speed, snow condition and gradient of terrain were not controlled in this study and these factors could have an effect on the data patterns. Development of algorithms to process the micro-sensor data into kinematic measurements would provide coaches and scientists with a valuable performance analysis tool. Further research is needed to develop such algorithms and to determine whether the patterns are consistent across a range of different speeds, snow conditions and terrain, and for skiers of differing ability.

Physiological characteristics of masters-level cyclists.

Peiffer, JJ, Abbiss, CR, Chapman, D, Laursen, PB, and Parker, DL. Physiological characteristics of masters-level cyclists. J Strength Cond Res 22(5): 1434-1440, 2008-Although a considerable amount of research is available describing the physiological characteristics of competitive young-adult cyclists, research describing these same characteristics in Masters-level cyclists is rare. Therefore, the purpose of this study was to describe and compare the effect of aging on physiological fitness parameters of Masters-level cyclists in an attempt to provide normative fitness data. Thirty-two male cyclists (35-73 years) completed one 15-minute economy test and one graded exercise test (GXT) on a cycle ergometer. During the GXT, maximal oxygen uptake (&OV0312;o2max), maximal heart rate (HRmax), the first (VT1) and second (VT2) ventilatory thresholds, and peak power output (PPO) were recorded. For the purpose of analysis, subjects were allocated into three age groups (35-45 years, 45-54 years, ≥55 years). Maximal oxygen uptake and absolute PPO were significantly lower among subjects 55 years and older (45.9 ± 4.6 mL·kg−1·min−1 and 324 ± 51 W, respectively) compared with the 45- to 54-year group (54.2 ± 6.6 mL·kg−1·min−1 and 392 ± 36 W, respectively), and both were significantly less compared with the 35- to 44-year group (60.7 ± 5.1 mL·kg−1·min−1 and 434 ± 32 W, respectively). Maximal heart rate was significantly greater in both the 35- to 44-year and 45- to 54-year age groups compared with the ≥55-year group. The first ventilatory threshold was significantly greater in the subjects who were 55 years and older group compared with the 35- to 44-year and 45- to 54-year age groups, and VT2 was significantly greater in subjects 55 years and older compared with the 35- to 44-year group. Economy was not different amongst groups. In conclusion, increases in age resulted in a significant reduction in fitness parameters across age groups. The comparison of the fitness characteristics of Masters-level cyclists with established young-adult cyclist data should be avoided, because this may lead to inaccurate assessments of fitness.