Hybrid-Training Method Increases Muscle Strength and Mass in the Forearm without Adverse Effect of Hand Function in Healthy Male Subjects

Abstract

Summary:Conventional neuromuscular electrical stimulation (NMES) results in surface muscle contraction but high electrical stimulation intensity is required to activate the deep muscles. Therefore, NMES is not useful for training at complicated sites such as the forearm. To make NMES more effective we developed a hybrid training method (HYB), consisting of electrically stimulated antagonists to resist agonist muscle contractions. The purpose of this study was to compare the effects of HYB on the forearm as compared with NMES alone, and to determine whether HYB had any adverse effects on complex hand movements. Thirty subjects were randomly distributed into three groups: a HYB program group, an isometric electrical stimulation group (ES), and a control group (CN). Subjects trained 3 times a week for 6 weeks. Each session consisted of 10 sets of 10 reciprocal 2-sec wrist flexions and extensions separated by 1-min rest intervals. Wrist flexion\extension torques, grip strengths (GS), forearm flexor\extensor cross sectional areas (CSA), and hand dexterity (Purdue Pegboard (PEG) test, finger tapping (Tapping) test were measured. The HYB group demonstrated statistically significant increases in wrist extension torques (22.8%, p<0.01), forearm flexor CSA (9.6%, p<0.01), and in forearm extensor CSA (5.1%, p<0.05) at the end of training. There was no increase in torque or CSA in the ES or CN groups. Hand dexterity showed no significant differences in any of the three groups. HYB had no adverse effect on hand function and was more effective in forearm training than NMES alone.

Changes in diffusion tensor imaging (DTI) eigenvalues of skeletal muscle due to hybrid exercise training

“…In the present study, extensor muscle strength increased post-HYBT, consistent with previous reports [13,14,16,[18][19][20]. We found no significant change in flexor strength, and here previous reports are variable [16,[18][19][20], and some do not report flexor strength [13,14].…”

“…We found no significant change in flexor strength, and here previous reports are variable [16,[18][19][20], and some do not report flexor strength [13,14]. In any case, in the present study training was more effective on extensors than flexors; the principal effectors of knee flexion, BF, ST, and SM showed the lower increase in CSA (2.5, 1.8, and 2.8%) than those of extensors (3.0%, 5.9%, 4.1%, and 5.6%).…”

“…HYBT creates resistance to the movement of a volitionally contracting agonist by means of the force generated by its electrically stimulated antagonist [13][14][15][16][17][18][19][20]. It has been shown to be practical and clinically effective in healthy young, elderly subjects [13,14,18,19], and NAFLD patients [18], yielding increasing muscle strength and mass in the upper and lower limb.…”

“…m r i j o u r n a l . c o m "hybrid training" (HYBT) developed in the University of Kurume, Japan [13][14][15][16][17][18][19][20]. We took this opportunity to study the DTI effects this lengthy training programme.…”

Strength Training Induces Greater Increase in Handgrip Strength than Wrestling Training per se

“…), have recently gained popularity in sports and rehabilitation settings for promotion of handgrip strength and for prevention and rehabilitation of hand-related injuries [9,10]. Previous studies that investigated the efficacy of various specialized handgrip strength training programs have been performed either in diseased individuals or in healthy untrained and physically active adults (young, middle-aged and elderly individuals), reporting either increases or no change on maximal handgrip strength [9][10][11][12][13]. However, the subjects' characteristics including age, training experience and health status are important contributing factors that could influence the efficacy of strength training program on improving indices of neuromuscular performance.…”