Contralateral versus ipsilateral protective effect against muscle damage of the elbow flexors and knee extensors induced by maximal eccentric exercise

The present study compared the ipsilateral repeated bout effect (IL-RBE) and contralateral repeated bout effect (CL-RBE) of the elbow flexors (EF) and knee flexors (KF) for the same interval between bouts to shed light on their mechanisms. Fifty-two healthy sedentary young (20–28 years) men were randomly assigned to the IL-EF, IL-KF, CL-EF, and CL-KF groups (n = 13/group). Thirty maximal eccentric contractions of the EF were performed in IL-EF and CL-EF, and 60 maximal eccentric contractions of the KF were performed in IL-KF and CL-KF, with a 2-week interval between bouts. Changes in muscle damage markers such as maximal voluntary contraction (MVC) torque, muscle soreness, and plasma creatine kinase activity, and proprioception measures before to 5 days post-exercise were compared between groups. Changes in all variables were greater (p \u3c 0.05) after the first than second bout for all groups, and the changes were greater (p \u3c 0.05) for the EF than KF. The changes in all variables after the second bout were greater (p \u3c 0.05) for the CL than IL condition for both EF and KF. The magnitude of the average protective effect was similar between CL-EF (33%) and CL-KF (32%), but slightly greater (p \u3c 0.05) for IL-EF (67%) than IL-KF (61%). These demonstrate that the magnitude of CL-RBE relative to IL-RBE was similar between the EF and KF (approximately 50%), regardless of the greater muscle damage for the EF than KF. It appears that the CL-RBE is more associated with neural adaptations at cerebrum, cerebellum, interhemispheric inhibition, and coricospinal tract, but the IL-RBE is induced by additional adaptations at muscles

Dietary Supplements and Sports Performance: Herbals

This is the fourth in a series of six articles to discuss the major classes of dietary supplements (vitamins; minerals; amino acids; herbs or botanicals; metabolites, constituents/extracts, or combinations). The major focus is on efficacy of such dietary supplements to enhance exercise or sport performance

Effects of simulated weightlessness on skeletal muscle structure and function in the upper arm

This investigation examined the effects of 4 weeks of non-dominant arm suspension on the functional and structural characteristics of the triceps brachii muscle of 6 normo-active college age males (age: 23.3 ±0.8 yrs, height: 176.1 ±3.7 cm, weight: 75.9 ±5.8 kg). The primary intent of this study was to determine if arm suspension is an effective analogue for simulating the effects of weightlessness on human skeletal muscle. Subjects were tested 2-3 days preceding suspension in a standard arm sling and immediately following removal of the sling. To suspend the arm the sling was worn during waking hours. Subjects were allowed to remove the sling during sleep and bathing. Specific instructions were given to avoid use of the arm. Torque production (Nm) during maximal isometric extensions at 90° significantly declined (p0.05) in the force-velocity attributes of the triceps over the other measured velocities (60, 90, 120, 180, 240, 300°/sec). Cross-sectional muscle area (CSA) of the upper arm diminished significantly (44.26 +2.66 to 42.43 ±2.54 cm2; 4%) following the 4 weeks of unloading (p0.05). Amplitude of the IEMG signal during maximal isometric contraction of the long head of the triceps fell (p<0.05) by 21 in response to the 4 week suspension period. The changes in triceps muscle structure and function found with arm suspension are similar in magnitude and direction to data obtained from humans following exposure to real and simulated weightlessness. These findings suggest that arm suspension may provide a useful model for simulating the effects of microgravity on human skeletal muscle.Thesis (Ph. D.)School of Physical Educatio

Single muscle fiber myosin heavy chain distribution in elite female track athletes

Contains fulltext : mmubn000001_027370747.pdf (publisher's version ) (Open Access)Promotor : G. Borst Pauwels121 p