[Diverting activity and restitution].
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Adult↗
Biomedical subjects
B Mazin
Publications and source records attributed to B Mazin.
Recuperation after muscular fatigue by "diverting activities".
"Diverting activity" is defined as any physical or mental activity performed between or simultaneously with bouts of exhaustive, local muscular work. In the present experiments bouts of exhaustive work consisting of rhythmic lifting of weights were performed with the elbow flexors or with the flexors of the middle finger. Pauses of 2 min duration spent in complete rest or while performing diverting activities alternated between the bouts of work. As diverting activities were used: Physical activity, dynamic or static, performed with big or small muscle groups (other than the fatigued group), or mental activity (problem solving). It was found that the amount of work that could be performed after a pause with diverting activity was always larger than the amount of work performed after a passive pause. The beneficial effect was seen also when the blood flow to the exhausted muscles was interrupted by pneumatic cuffs. Determination of the blood flow in the exhausted muscles by means of Xe-133 clearance showed no systematic blood flow increases caused by the diverting activity. It is concluded that recuperation after local muscle fatigue is influenced by a central nervous factor (Setchenov phenomenon) that is largely independent of the local blood flow.
Activity Cycles↗
A central nervous component in local muscular fatigue.
It has been shown previously (this journal) that any activity, physical or mental, performed as "diverting activity" in the pauses between bouts of exhaustive musclar work has a positive effect on the recuperation after fatigue. It was concluded that this effect was primarily of central nervous origin (Setchenov, 1903) and not a circulatory effect (Weber, 1914). In the present experiments it is shown that the amount of work that can be performed before exhaustion is larger when the subjects work with their eyes open than when they work with closed eyes. Further, when complete exhaustion has been reached with closed eyes, opening of the eyes results in an immediate return of a working capacity amounting to 15-30% of that already performed. It is demonstrated, that patellar reflexes are brisker when the eyes are open than when they are closed. The same is the case during the diverse forms of "diverting activity" used in this and the previous article. The brisker myotatic reflexes are taken to mean an enhanced central nervous arousal, and the recuperative effect of "diverting activity" is consequently explained as being due to an increased facilitation of the neuro-motor system, which in fatigue is inhibited centrally through afferents from receptors in the fatigued muscles.
Adolescent↗