Four weeks of high- versus low-load resistance training to failure on the rate of torque development, electromechanical delay, and contractile twitch properties

• Published in: Journal of musculoskeletal & neuronal interactions Vol. 16; no. 2; pp. 135 - 144
• Main Authors: Jenkins, N Dm, Housh, T J, Buckner, S L, Bergstrom, H C, Smith, C M, Cochrane, K C, Hill, E C, Miramonti, A A, Schmidt, R J, Johnson, G O, Cramer, J T
• Format: Journal Article
• Language: English
• Published: Greece International Society of Musculoskeletal and Neuronal Interactions 01-06-2016
• Subjects: Elbow Joint; Electromyography; Humans; Isometric Contraction - physiology; Male; Muscle Strength - physiology; Muscle, Skeletal - physiology; Original; Resistance Training - methods; Torque; Young Adult
• ISSN: 1108-7161

The purpose of this study was to investigate the effects of 4-weeks of high- versus low-load resistance training to failure on rate of torque development (RTD), electromechanical delay (EMD), and contractile twitch characteristics. Fifteen men (mean±SD; age=21.7±2.4 yrs) were randomly assigned to either a high- (80% 1RM; n=7) or low-load (30% 1RM; n=8) training group and completed elbow flexion resistance training to failure 3 times per week for 4 weeks. The participants were tested at baseline, 2-, and 4-weeks of training. Peak RTD (pRTDV) and RTD at 0-30 (RTD30V), 0-50 (RTD50V), 0-100 (RTD100V), and 0-200 (RTD200V) ms, integrated EMG amplitude (iEMG) at 0-30, 0-50, and 0-100 ms, and EMD were quantified during maximal voluntary isometric muscle actions. Peak twitch torque, peak RTD, time to peak twitch, 1/2 relaxation time and the peak relaxation rate were quantified during evoked twitches. Four weeks of high-load, but not low-load resistance training, increased RTD200V. There were also increases in iEMG during the first 30 ms of muscle activation for the high- and low-load groups, which may have indirectly indicated increases in early phase motor unit recruitment and/or firing frequency. There were no significant training-induced adaptations in EMD or contractile twitch properties.