Fiber Type Composition and Rate of Force Development in Endurance- and Resistance-Trained Individuals

Abstract

The purpose of the study was to investigate the relationship between muscle fiber composition and the rate of force development (RFD) in well-trained individuals with different training background. Thirty-eight young males with different training background participated: 9 endurance runners, 10 power-trained, 9 strength-trained, and 10 sedentary. They performed maximal isometric leg press for the measurement of RFD. Body composition (dual x-ray absorptiometry) and vastus lateralis fiber type composition was also evaluated. When all participants were examined as a group, moderate correlations were found between the percent of type II muscle fibers and RFD between 100-600ms (r: 0.321 - 0.497, p<0.05). The correlation coefficients were higher for the cross-sectional area (CSA) and the %CSA of type II and IIx muscle fibers (r: 0.599 - 0.847, p<0.001). For the power group, RFD up to 250ms was highly correlated with % type IIx muscle fibers and type IIx fiber CSA (r: 0.670 - 0.826, p<0.05), as well as with %CSA of type IIx fibers (r: 0.714 - 0.975, p<0.05). Significant correlations were found between the relative RFD (·kg lower extremities lean mass) and CSA-%CSA of type II and IIx fibers for the power group (r: 0.676 - 0.903, p<0.05). No significant correlations were found between muscle morphology and RFD for the other groups. In conclusion, the present data suggest that there is a strong link between the type IIx muscle fibers and early RFD and relative RFD in power-trained participants. Type II fibers seem to be moderately linked with RFD in non-power-trained individuals.

Yank: the time derivative of force is an important biomechanical variable in sensorimotor systems

“…In the muscle contractile processes, crossbridge cycling rates have been estimated to be as much as 4 times slower in type I versus type II muscle fibers (He et al, 2000). As a consequence, it has long been assumed that a higher proportion of type II fibers, which can be induced via training, contributes to a larger yank (Methenitis et al, 2017). Moreover, a key to understanding how the plasticity of fiber type influences yank is that when muscles are activated from rest, the slack of the tendon and lower compliance of the tendon's toe region can cause rapid shortening of the muscle (Edman and Josephson, 2007;Krylow and Rymer, 1997).…”

The Importance of Lean Body Mass for the Rate of Force Development in Taekwondo Athletes and Track and Field Throwers

“…Throwers were seated on a custom-made completely rigid leg press chair made of steel with rigid plywood boards and placed both their feet on the force platform (Applied Measurements Ltd. Co., Aldermaston, Berkshire, UK, WP800, 1000 kg weighting platform, 80 × 80 cm, sampling frequency 1 kHz), which was positioned perpendicular on a concrete laboratory wall. Knee angle was set at 120 • and hip angle was set at 100 • [7,8,13,30,31]. After three sub-maximal efforts, athletes were instructed to apply their maximum force as fast as possible for 3 s. Three maximum efforts with 3-min rest were performed while athletes were vocally encouraged to perform their maximum.…”

“…Rate of force development was calculated as the mean tangential slope of the force-time curve in specific time windows of 0-30, 0-50, 0-80, 0-100, 0-150, 0-200, and 0-250 ms, relative to the onset of contraction which was set at 2.5% of the difference between baseline and maximum force; e.g., RFD = DForce/DTime [1,32]. Early RFD includes the previously mentioned time points until the first 100 ms from the onset of a muscle contraction, while late RFD the time points over the first 100 ms from the onset of a muscle contraction [2,7,8,32,33]. Sequential RFD time windows were analyzed, including 30-50 ms, 50-80 ms, 80-100 ms, 100-150 ms, 150-200 ms, and 200-250 ms, while isometric force production expressed per percentage of maximum voluntary contraction (%MVC) in all time windows [(Fms/MVC)·100] was also calculated.…”

“…RFD is influenced by different factors at early (<100 ms) and late phases (>100 ms) from the onset of muscle contraction [2,7,8]. The early phase of RFD is thought to be determined mainly by the neural drive to the muscle, as well as the muscle fiber type composition [2,[7][8][9].…”

“…The early phase of RFD is thought to be determined mainly by the neural drive to the muscle, as well as the muscle fiber type composition [2,[7][8][9]. Late phase RFD is largely influenced by maximal strength and most likely muscle mass, as suggested by studies reporting parallel changes in maximal muscle strength and contractile RFD 150-250 ms from the onset of contraction [1,2,7,8,[10][11][12][13]. Nevertheless, little is known about the correlation between muscle mass and RFD in power athletes.…”