Remarks on the effect of resistance exercise upon the circulation in man, local and general / by T. Lauder Brunton and F.W. Tunnicliffe.

  • Brunton, Thomas Lauder, Sir, 1844-1916.
Date:
1897
Catalogue details

Licence: Public Domain Mark

Credit: Remarks on the effect of resistance exercise upon the circulation in man, local and general / by T. Lauder Brunton and F.W. Tunnicliffe. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

    8/15 (page 6)
    arteries subsequent to muscular contraction. The muscle which we chose for this purpose was the gastrocnemius. The subject was placed in the supine position, with the leg slightly raised. At a given moment he was directed to extend the foot by contracting the muscles of the calf, the movement of the foot being the while resisted, so that very little if any shortening of the muscles occurred. The muscles were kept in a condition of contraction for the desired time, at the expiration of which time the subject was directed to desist. The apparatus which we used to obtain the following tracing was designed by one of us (Tunnicliffe) in conjunction with Professor Mosso, of Turin, and has received the name of myosphygmometer. It will be fully described elsewhere; suffice it to say here that we regard the above tracing as a muscular sphygmogram. This sphygmogram, which for the sake of convenience has (Fig. 2) been split up into three parts (a, b, c) was taken continuously, the sphygmo- manometer being kept in position during the entire experi- ment. The changes in the pulse occurring subsequently to contraction are best seen by reference to these curves (Fig. 2). Curve a requires no explanation. It will be seen that both the respiratory and vascular oscillations of pressure are manifest in it, and hence it may be taken as a sensitive index of the changes occurring in the vessels. Concerning the Curve b, or the one taken during contraction, we are at present unable to make any exact statement with re- gard to the condition of the vessels during this period. It is Eossible that the fibrillar twitchings which occur when the elly of a muscle like the gastrocnemius is thrown volun- tarily into contraction may be responsible, probably are in some part, for the masking of the arterial pulsations during contraction. Another, and to us a more probable explana- tion, is that the result is in the main due to a partial occlu- sion of the intramuscular arteries and arterioles during the period of contraction. This explanation would be in accord with the observations of Ludwig and Gaskell, that during a short tetanus, after the first jet-like rush of blood, the flow from the efferent vein may fall to practically nil, or, in other words, the vessels may have their calibre practically occluded. With regard to change in the sphygmogram after con- traction, there is much less room for uncertainty. If we examine the post-contraction sphygmogram, and com- pare it with the sphygmogram taken before contraction, we shall see that although the pulse frequency has remained practically the same, the pulse itself has become considerably altered. The pulsations are larg er, nearly double their former size, and the relative position of the dicrotic notch is altered. The inference one can draw from this is that the arteries have increased in diameter, and are relatively fuller than they were before the contraction. If we now direct our attention to the end of the curve we shall see that the last few pulses which are registered are almost identical with those occurring before the contraction. If we reckon this in time it means that a contraction lasting one minute produces an arterial dilatation lasting half a minute. Having considered the local and general changes in the circulation in man consequent upon the practice of resistance exercises, the question which naturally arises is how far the local changes explain the general ones. There can be little doubt that the fall in general pressure which always follows