Kevin W. McCurdy

The Effects of Short-Term Unilateral and Bilateral Lower-Body Resistance Training on Measures of Strength and Power

The purpose of this study was to compare the effects of short-term unilateral resistance training (UL) and bilateral resistance training (BL) with free weights on several tests of unilateral and bilateral lower-body strength and power in men and women. Thirty-eight untrained men and women (mean body mass 78.3 ± 21.47 kg; age 20.74 ± 2.6 years) completed the study. The groups trained 2 days per week for 8 weeks with free weights and 2 days per week for 5 of the 8 weeks with plyometric drills. The resistance-training program consisted of a progression from 3 sets of 15 repetitions at 50% of the subjects predicted 1 repetition maximum (1RM) to 6 sets of 5 repetitions at 87% 1RM. Training volume and intensity were equal for each group. The free-weight squat was used to measure unilateral and bilateral strength. Power was measured by the Magaria-Kalamen stair-climb test and the unilateral and bilateral vertical jump test. Analysis of covariance was used to analyze differences between men and women and the interaction of group and gender. Pretest scores were used as the covariate. The UL group improved more than the BL group on the unilateral vertical jump height (p = 0.001) and relative power (p = 0.013). After adjusting for pretest differences, the improved scores on all tests, except for the unilateral squat, were similar between the men and the women. No significant interactions on all tests were found for the men or women comparison between training groups. These results indicate that UL and BL are equally effective for early phase improvement of unilateral and bilateral leg strength and power in untrained men and women.

The validity and reliability of the 1RM bench press using chain-loaded resistance

The purposes of this study were to determine the validity and test-retest reliability of the 1 repetition maximum (1RM) chain-loaded, free-weight bench press (CBP) and to examine possible learning effects that may occur between the test-retest measurements. Nine resistance-trained men (20.58 ± 1.31 years, 188.24 ± 9.29 cm, 92.07 ± 16.94 kg) and seven resistance-trained women (20.42 ± 0.98 years, 175.61 ± 9.32 cm, 73.61 ± 10.80 kg) participating in Division II college basketball completed this study. Two familiarization sessions took place using light to moderate loads to learn proper technique. The subjects completed a 1RM test on the traditional plate-loaded bench press 4 days before completion of the CBP 1RM, which was followed by 4 days of rest before completing the retest. Intraclass correlation coefficients (ICC) and the percent coefficients of variation (CV) were used to determine relative and absolute test-retest reliability. Concurrent validity was determined from the Pearson correlation coefficients between the CBP and the plate-loaded bench press. Test-retest differences were analyzed with the paired t-test. ICC and CV for the men (r = 0.99, 1.4%) and women (r = 0.93, 3.5%), respectively indicate that highly reproducible 1RM scores can be found with the CBP. High validity was also found with high correlations between the CBP and plate-loaded bench press for the men (r = 0.95) and women (r = 0.80). A statistically significant (p = 0.04) but clinically small (2.57 kg) shift in the mean occurred between the CBP test and retest for the men, whereas no change occurred for the women. The data indicate that valid and reliable 1RM scores can be found after two familiarization sessions in men and women athletes who have previous resistance training experience.

Comparison of Chain- and Plate-loaded Bench Press Training on Strength, Joint Pain, and Muscle Soreness in Division Ii Baseball Players

McCurdy, K, Langford, G, Ernest, J, Jenkerson, D, and Doscher, M. Comparison of chain- and plate-loaded bench press training on strength, joint pain, and muscle soreness in Division II baseball players. J Strength Cond Res 23(1): 187--195, 2009-The purpose of this study was to investigate the effects of chain- (CBP) and plate-loaded (PBP) bench press training on measures of strength, shoulder pain, and muscle soreness in Division II baseball players. Twenty-eight subjects with previous resistance training experience (4.8 ± 2.7 years) completed the study while participating in off-season baseball practice. All subjects completed a one-repetition maximum pre- and posttest on the CBP and PBP and reported shoulder pain and muscle soreness on 15 occasions during training. Two treatment groups, CBP and PBP, trained 2 d·wk−1 for 9 weeks during the off-season with a linear periodization strength training program. The CBP group used chains attached to the bar as the entire load, and the PBP group used only traditional plate-loaded resistance. The chains provided a variable resistance, with a reduction in load during the descent as the weight collected on the floor and with the load increasing during ascent as the weight was lifted from the floor. Statistically significant increases were found in strength scores after training for the CBP test (p < 0.001) and the PBP test (p < 0.001). Both groups were able to improve strength on the CBP and PBP, but no significant differences were found in strength gains between the groups on the CBP and PBP tests. Although levels of pain and soreness were not significantly different, a threefold difference was found for perceived levels of shoulder pain (mean totals of 2.15 vs. 6.14), whereas reported soreness was similar (9.38 vs. 10.57) for the CBP and PBP group, respectively. The data indicate that training with chain- and plate-loaded resistance produce similar short-term strength improvement on the chain- and plate-loaded bench press. Baseball players may benefit from CBP training with improved free-weight strength while minimizing shoulder stress.

Specificity of machine, barbell, and water-filled log bench press resistance training on measures of strength.

The purpose of this study was to compare the effects of 10 weeks of resistance training with an isotonic bench press machine and 2 types of free-weight bench press exercises on several measures bench press strength. Specificity was investigated by comparing the ability to transfer strength gained from a type of training that differed from the mode of testing. Forty-nine men participated in the study. The subjects completed a pretest on the machine (MB), barbell (BB), isokinetic (IB), and log (LB) bench press to determine baseline strength and completed 10 weeks of training on the MB, BB, or LB. The 3 groups were tested to see whether differential training effects occurred from pre- to post- test scores on the BB, MB, LB, and peak force on the IB. By multivariate analysis, the trial-by-group interaction was not statistically significant. The multivariate and subsequent univariate analyses of variance tests indicated statistically significant effects from pre- to posttest for peak force on the IB test and the BB, MB, and LB. Correlations among the strength tests were high (0.92 ≥ r ≤ 0.97) and moderate between the strength tests and IB peak force (0.62 ≥ r ≤ 0.83). Mean 3 repetition maximum MB strength was 8% higher than BB strength, which was 3% higher than LB strength, indicating differences in the amount of stabilization required to control the resistance. The findings of this study showed that all 3 training groups significantly improved in strength during short-term training on the MB, BB, and LB. These data lend evidence that improved strength after training on the MB, BB, and LB equally transfers to strength gains on any of the 4 modes of testing. These results should be considered when including similar exercises varying in stability into the training program to improve strength.