The effects of eccentric arm crank training - A pilot study

Abstract

Background Strength training plays an important role in a holistic training approach, not only for athletes but also for patients looking to (re)gain strength during rehabilitation. In the past few years, eccentric strength training has received increased attention as this type of training increases muscle strength more than conventional training methods (Douglas et al., 2017). Since eccentric strength training includes higher levels of mechanical tension and leads to greater exercise-induced muscle damage compared to concentric training, the training protocol should be implemented with caution and effects may appear after a longer recovery period (Douglas et al., 2017). Whereas lower body training has been studied extensively, only little data is available regarding eccentric strength training for the upper body, particularly in either wheelchair athletes or individuals with a spinal cord injury. We wanted to investigate if strength training on a specially designed eccentric arm crank ergometer (Krafttraining mittels exzentrischer Handkurbel, KREHA) can improve performance as well as the maximum strength of the upper body. In this pilot study, we investigated the feasibility of the training protocol in healthy individuals. Methods Thirteen healthy, physically active and strength training experienced participants (median [interquartile range] age 29 [5] years, nine women) participated in the study. The participants followed the eccentric arm crank training protocol besides their usual daily training routine. The performance tests and training at the KREHA were familiarized one week before the pretests (Pre) took place. The test battery consisted of a bench press (one-repetition maximum [1RM]), a Wingate test (peak and mean power) and a VO2max test (Wmax) on a regular arm crank ergometer, as well as grip strength and an upper arm circumference measurement. The training protocol consisted of 20 progressive training sessions on the KREHA. The training sessions were planned based on individual peak power using a double progression method for duration and intensity, and lasted between 8 to 14 minutes at an intensity of 20-50% of peak power. The sessions were spread over a maximum of 12 weeks, with no more than three sessions per week. Posttests consisted of the same test battery as the pretests and were scheduled 5-11 days (Post1) respectively four weeks (Post2) after the last training. Results The 1RM (39 [18] to 44 [18] kg), peak power (357 [143] to (360 [154] W) and mean power (263 [108] to 274 [135] W) improved over the training duration (Pre-Post1, p < 0.05). Likewise, the upper arm circumference increased from 28.4 (3.5) to 29.5 (4.0) cm (p < 0.05). 1RM, peak power and mean power remained higher four weeks after the last training (Pre vs. Post2, p < 0.05). Grip strength remained similar at all time points (p = 0.2). Conclusions Participants were able to improve their aerobic and anaerobic performance between 1-4% as well as the maximum strength of the upper body by 13% through eccentric arm-crank training. In two future studies, the training concept will be investigated in wheelchair athletes and patients with a spinal cord injury.

Keywords

• eccentric
• strength training
• upper body
• arm-cranking