Faster early rate of force development in warmer muscle: an in vivo exploration of fascicle dynamics and muscle-tendon mechanical properties.

Although heat exposure has been shown to increase the skeletal rate of force development (RFD), the underlying processes remain unknown. This study investigated the effect of heat on gastrocnemius medialis (GM) muscle-tendon properties and interactions. Sixteen subjects performed electrically evoked and voluntary contractions combined with ultrafast ultrasound under thermoneutral [control (CON): 25.

Hyperthermia reduces electromechanical delay via accelerated electrochemical processes.

The present study aimed to determine the effect of hyperthermia on both electrochemical and mechanical components of the electromechanical delay (EMD), using very-high-frame-rate ultrasound. Electrically evoked peak twitch force, EMD, electrochemical (D; i.e.

Influence of joint angle on muscle fascicle dynamics and rate of torque development during isometric explosive contractions.

This study investigated how joint angle influences fascicle shortening dynamics of gastrocnemius medialis (GM) during explosive contractions and the resulting impact on rate of torque development (RTD). Sixteen participants performed six sets of five maximal explosive voluntary isometric plantar flexions at -20°, -10°, 0° (neutral position), 10°, 20°, and 30° of ankle angle and five no-load ballistic plantar flexions. RTD assessed over all time windows (from 0 to 200 ms) was significantly lower in extreme plantar flexed (≥20°) and dorsiflexed (-20°) positions compared with -10, 0° (475 ± 105 N·m·s), and 10°.

Mechanical determinants of forward skating sprint inferred from off- and on-ice force-velocity evaluations in elite female ice hockey players.

This study aimed to investigate the correlations between players' mechanical capacities determined during off- and on-ice tests. Whole body force-velocity relationships were assessed in elite female ice hockey players ( = 17) during jumping [squat jump (SJ)], running (5 and 30 m) and skating (5 and 40 m) sprint tasks. Mechanical capacities estimates include relative maximal theoretical force (F), velocity (V), power (P), slope of the linear relationship between force relative to body mass and velocity (S), maximal horizontal component of the ground reaction force to the corresponding resultant force (RF) and minimal rate of decrease of this ratio (D).

The slack test does not assess maximal shortening velocity of muscle fascicles in humans.

The application of a series of extremely high accelerative motor-driven quick releases while muscles contract isometrically (i.e. slack test) has been proposed to assess unloaded velocity in human muscle.