Short-term creatine supplementation does not improve muscle activation or sprint performance in humans

Abstract

The purpose of this study was to examine the influence of short-term creatine (Cr) supplementation on exercise-induced transverse relaxation time (T2) and sprint performance during maximum intermittent cycling exercise using the muscle functional magnetic resonance imaging (mfMRI) technique. Twelve men were divided into a Cr supplementation group [the Cr group, taking 4 x (5 g Cr monohydrate + 2.5 g maltodextrin)/day], or a placebo supplementation group (the P group, taking 4 x 7.5 g maltodextrin/day). The allocation to the groups was based on cycling tests and the subject's physical characteristics, and thus was not randomized. A double-blind research design was employed for a 5-day supplementation period. mfMR images of the right thigh were collected at rest and immediately after two, five, and ten 6-s sprint bouts of maximum intermittent cycling exercise with a 30-s recovery interval between sets. Before and after supplementation, blood was taken to calculate lactate accumulation, and the muscle volume of the thigh was determined by MRI. Following supplementation, there was significant body mass gain in the Cr group ( P<0.05), whereas the P group did not change. The exercise-induced T2, blood lactate levels and sprint performance were not affected by Cr supplementation in any sprint bouts. These results suggest that short-term Cr supplementation does not influence short duration repetitive sprint performance and muscle activation and/or metabolic state during sprint cycling evaluated by mfMRI of the skeletal muscle in humans.

Atrophy of thigh muscles after meniscal lesions and arthroscopic partial menisectomy

“…The volume of the AD muscle group showed no significant difference between the operated and non-operated limb. Although the real function of the AD muscle during movement, including that in daily life, is not well known, recent studies have revealed that this muscle group is involved in basic human movements such as running and cycling [2,13,15,17]. We showed that this muscle group did not decrease in volume, thus the effect of the AD on these movements would be less after the surgery.…”

Thigh muscle activation distribution and pulmonary V̇o2kinetics during moderate, heavy, and very heavy intensity cycling exercise in humans

“…For example, it offers the opportunity to investigate all the muscles engaged in the external work rather than those regions proximal to surface electrodes and allows spatial mapping of muscle "activity" during exercise. In the present study, we used this property to investigate activity patterns (2,4,18,25,33) in a cross section of 10 leg muscles during cycle ergometry over a range of intensities.…”

Use of electromyography to detect muscle exhaustion in finishing barrows fed ractopamine HCl1

“…AU = arbitrary units. Kinugasa et al (2004) and Racinais et al (2007). Therefore, of the muscles analyzed, it is possible the reduction of ambulatory movement in pigs fed a RAC diet may be due to a reduction in muscle fiber recruitment in the ST, a muscle that is important in extending the hip, stifle, and hock and flexes the stifle when the leg is lifted .…”