Harsh H. Buddhadev

Postresistance exercise ethanol ingestion and acute testosterone bioavailability.

INTRODUCTION Alcohol (ethanol) and resistance exercise can independently affect circulating bioavailable testosterone concentration. PURPOSE The purpose of this study was to examine the testosterone bioavailability and the anabolic endocrine milieu in response to acute ethanol ingestion after a bout of heavy resistance exercise. METHODS Eight resistance-trained men (mean ± SD: 25.3 ± 3.2 yr, 87.7 ± 15.1 kg, 177 ± 7 cm) completed two identical acute heavy resistance exercise tests (AHRET: six sets of 10 repetitions of Smith machine squats) separated by 1 wk. Post-AHRET, participants consumed either 1.09 g of grain ethanol per kilogram lean mass (EtOH condition) or no ethanol (placebo condition). Blood samples were collected immediately before exercise (PRE), immediately after exercise (IP), and every 20 min postexercise for 300 min. Samples after IP were pooled into phases (20-40 min, 60-120 min, and 140-300 min after exercise) and analyzed for total testosterone (TT) and free testosterone (FT), sex hormone-binding globulin (SHBG), cortisol, and estradiol. RESULTS Peak blood ethanol concentration (0.088 ± 0.015 g·dL) was achieved 60-90 min postexercise. TT and FT were elevated significantly (P ≤ 0.05) at IP for both conditions. At 140-300 min postexercise, TT, FT, and free androgen index were significantly higher for EtOH (TT: 22.5 ± 12.5 nmol·L; FT: 40.5 ± 7.6 pmol·L) than for placebo (TT: 13.9 ± 6.8 nmol·L; FT: 22.7 ± 10.0 pmol·L). No differences between conditions were noted for SHBG, cortisol, or estradiol. CONCLUSION Postexercise ethanol ingestion affects the hormonal milieu including testosterone concentration and bioavailability during recovery from resistance exercise.

Smith Machine Counterbalance System Affects Measures of Maximal Bench Press Throw Performance

Vingren, JL, Buddhadev, HH, and Hill, DW. Smith machine counterbalance system affects measures of maximal bench press throw performance. J Strength Cond Res 25(7): 1951-1956, 2011—Equipment with counterbalance weight systems is commonly used for the assessment of performance in explosive resistance exercise movements, but it is not known if such systems affect performance measures. The purpose of this study was to determine the effect of using a counterbalance weight system on measures of smith machine bench press throw performance. Ten men and 14 women (mean ± SD: age, 25 ± 4 years; height, 173 ± 10 cm; weight, 77.7 ± 18.3 kg) completed maximal smith machine bench press throws under 4 different conditions (2 × 2; counterbalance × load): with or without a counterbalance weight system and using ‘light’ or ‘moderate’ net barbell loads. Performance variables (peak force, peak velocity, and peak power) were measured using a linear accelerometer attached to the barbell. The counterbalance weight system resulted in significant (p < 0.001) reductions in measures of peak force (mean difference ± standard error: light: −112 ± 20 N; moderate: −140 ± 23 N), peak velocity (light: −0.49 ± 0.10 m·s−1; moderate: −0.33 ± 0.07 m·s−1), and peak power (light: −220 ± 43 W; moderate: −143 ± 28 W) compared with no counterbalance system for both load conditions. Load condition did not affect absolute or percentage reductions from the counterbalance weight system for any variable. In conclusion, the use of a counterbalance weight system reduces accelerometer-based performance measures for the bench press throw exercise at light and moderate loads. This reduction in measures is likely because of an increase in the external resistance during the movement, which results in a discrepancy between the manually input and the actual value for external load. A counterbalance weight system should not be used when measuring performance in explosive resistance exercises with an accelerometer.

Effects of age and physical activity status on redistribution of joint work during walking

During walking older adults rely less on ankle and more on hip work than young adults. Disproportionate declines in plantarflexor strength may be a mechanism underlying this proximal work redistribution. We tested the hypothesis that proximal redistribution is more apparent in older compared to young adults and in sedentary compared to active individuals over multiple walking speeds. We recruited 18 young (18-35 yrs) and 17 older (65-80 yrs) physically active and sedentary adults. Participants completed five trials at four walking speeds as marker positions and ground reaction forces were collected. Sagittal plane net joint moments were computed using inverse dynamics. Instantaneous joint powers for the ankle, knee, and hip were computed as products of net joint moments and joint angular velocities. Positive joint work was computed by integrating hip, knee, and ankle joint powers over time in early, mid, and late stance, respectively. Relative joint work was expressed as a percentage of total work. Isokinetic strength of lower limb flexor and extensor muscles was measured. Older adults had lower relative ankle (p=0.005) and higher relative hip (p=0.007) work than young adults for multiple speeds. Non-significant trends (p<0.10) indicating sedentary participants had lower relative ankle (p=0.068) and higher relative hip work (p=0.087) than active adults were observed. Age-related differences in plantarflexor strength were not disproportionate compared to strength differences in knee and hip musculature. Age influenced proximal work redistribution over multiple walking speeds. Physical activity status showed a similar trend for proximal work redistribution, but failed to reach statistical significance.

Mechanisms underlying the reduced performance measures from using equipment with a counterbalance weight system.

Buddhadev, HH, Vingren, JL, Duplanty, AA, and Hill, DW. Mechanisms underlying the reduced performance measures from using equipment with a counterbalance weight system. J Strength Cond Res 26(3): 641–647, 2012—Bench press throws are commonly used in the assessment of upper-body power and are often performed on a Smith machine that uses a counterbalance weight to reduce the net load on the barbell. The use of a counterbalanced Smith machine was recently shown to reduce performance measures, but the mechanisms for this reduction have not been established. The purpose of this study was to determine the underlying physiological and biomechanical causes of the reduced performance measures found when using a counterbalanced Smith machine. Twenty-four men (mean ± SE: age, 23 ± 1 years; weight, 91.0 ± 3.5 kg; height, 178.9 ± 1.2 cm) performed Smith machine bench press throws at 30% of 1-repetition maximum under 4 conditions: (a) rebound movement and counterbalance, (b) rebound movement and no counterbalance, (c) concentric-only movement and counterbalance, and (d) concentric-only movement and no counterbalance. Peak power, peak force, and peak concentric and eccentric velocities were measured using a linear accelerometer, and peak ground reaction force was measured using a force plate. The counterbalance condition produced significantly (p < 0.05) lower peak accelerometer-based force (−21.2 and −17.0% for rebound and concentric-only bench press throws, respectively) but increased peak ground reaction force (5.3 and 3.2%). The discrepancy between changes in peak accelerometer-based force and peak ground reaction force suggests that an increase in net external load occurred during the movement. For performance testing of explosive movements, the use of a counterbalance system results in an underestimation of performance capability, likely because of an increase in the net external load during the concentric phase. Therefore, a counterbalance system should not be used for explosive movement performance testing.

Acute Effects of Two Hip Flexor Stretching Techniques on Knee Joint Position Sense and Balance: 1671 Board #6 May 31 3

Background Tightness of hip flexor muscles has been recognized as a risk factor for various musculoskeletal injuries in the lower extremities. Purpose The purpose of this study was to examine the acute effects of two hip flexor stretching techniques (dynamic and hold-relax proprioceptive neuromuscular facilitation, HR-PNF) on hip extension (ROM), knee joint position sense (JPS) and balance in healthy college age students who exhibit tightness in hip flexor muscles. Study Design Pretest-posttest randomized experimental groups. Methods Thirty-six healthy college age students (mean = 22.37 years) with tight hip flexors participated in this study. Hip extension ROM, knee joint position sense and dynamic balance were tested pre- and post-stretching using a digital inclinometer, an iPod touch and the Y-Balance test, respectively. Subjects were randomly divided into dynamic and HR-PNF stretching groups. Three-way mixed analysis of variance was utilized to explore if an interaction existed between the groups in tested variables. Results There was a significant effect of time on hip extension ROM in both groups (p < 0.001). There was also a significant effect of stretch type on hip extension ROM (p = 0.004) favoring hold-relax over dynamic stretching group. There was a non-significant effect of time on mean knee joint position replication error in both groups. There was a significant main effect of time on the Y-Balance tests mean distance of reach to posteromedial and posterolateral directions (p < 0.001). There was also a significant main effect of directions of reach on distances achieved (p < 0.001) favoring posterolateral over posteromedial, and the latter over anterior direction. Conclusions The results of this study demonstrated the effectiveness of both HR-PNF and dynamic stretching techniques which resulted in a significant acute improvement in hip extension ROM and dynamic balance measures, with HR-PNF being more effective than dynamic stretch. However, there were no significant improvements in knee joint position replication over time in either stretching group. Level of Evidence 2b.

Use of Counter-balanced Smith Machine Affects Performance Measurements for Rebound Bench Press Throws: 1457

Rebound bench presses throws (RBT), often performed on a Smith machine, are used for assessment and training of upper body power. During a RBT, the stretch-shortening cycle potentiates performance in the concentric movement. Smith machines frequently utilize a counter-balance weight to reduce the net load on the barbell; however, the use of counter-balance weight affects measures of performance for RBT. PURPOSE: To evaluate how the use of a counter-balanced Smith machine affects performance measures for RBT. METHODS: Performance measures for the no counter-balanced (NCB) and counter-balanced (CB) RBT were assessed for 24 men (age: 23 ± 3 years, height: 179 ± 6 cm, mass: 91 ± 17 kg, bench press 1repetition maximum [1RM]: 107 ± 18 kg). Each participant performed 2 sets of 2 repetitions of RBT for each condition at 30 % of their 1RM. Peak power, peak force, peak concentric and eccentric velocities, and duration of eccentric and concentric phases were measured using a linear accelerometer attached to the barbell; peak ground reaction force (GRF) was measured using a force plate. For each condition, data from the repetition with the highest peak power was used in further analyses. Peak EMG was measured for the right pectoral, deltoid and triceps muscles and normalized using peak EMG in the 1RM. RESULTS: Peak barbell measurements for power (NCB: 1220 ± 269 W, CB: 1069 ± 255 W), force (NCB: 906 ± 252 N, CB: 713 ± 143 N), and concentric (NCB: 2.54 ± 0.27 m·s-1, CB: 2.24 ± 0.32 m·s-1) and eccentric (NCB: -1.19 ± 0.46 m·s-1, CB: -0.95 ± 0.29 m·s-1) velocities were significantly (p<0.05) higher for NCB compared to CB. The durations for the eccentric (NCB: 0.53 ± 0.16 s, CB: 0.64 ± 0.12 s) and concentric phases (NCB: 0.58 ± 0.58 s, CB: 0.77 ± 0.82 s), and peak pectoral EMG (NCB: 91 ± 21 % of 1RM, CB: 101 ± 24 % of 1RM) were lower for NCB compared to CB. Peak EMG for deltoid and triceps and peak GRF were unaffected by the use of counter-balance weights. CONCLUSION: The use of CB equipment resulted in reduced performance measurements (peak power, peak force, and peak eccentric and concentric velocities) for the RBT compared to NCB equipment. The lower peak eccentric stretch velocity likely resulted in a less effective stretch-shortening cycle for CB compared to NCB and thus helps explain the lower performance measurements found for CB.