Joseph Royce

Isometric Fatigue Curves in Human Muscle with Normal and Occluded Circulation

Abstract Fatigue curves for the forearm muscles during sustained isometric contraction were obtained on 24 young men. No difference was found between the curves obtained with and without artificial occlusion of the circulation, down to the point where the exerted force became less than approximately 60 per cent of the maximal strength. Below this critical level, the exerted force continued to diminish under the occluded condition, but leveled off when there was no occlusion. The leveling off was explained as due to the systolic blood pressure being higher than the prevailing intra-muscular pressure at this stage of fatigue. A mathematical equation, the components of which were derived from broad physiological considerations of the factors involved, fitted the observed data accurately.

Rate of muscle tension development and release under extreme temperatures.

Summary and ConclusionsThirty-one male subjects squeezed a hand dynamometer as rapidly and as forcefully as possible, the effort being recorded on fast-moving paper. At the count of three the hand was released explosively. Two such testing sessions were held; following the first measurement of tension development and release the subject immersed his arm in a water bath. On one occasion it was at a temperature of 10° C, on the other of 46° C.The subject then repeated the procedure with the hand ergograph. The force-time curves of the contraction were described mathematically by a three-component exponential equation. Very little difference existed in the rate parameters of the normal and hot conditions, but these parameters were markedly slowed by the application of cold. This was further reflected in the contributions that each component made to the total work integral. Similar results were obtained during the release phase; the rates were nearly identical for the normal and hot curves, but two or three times slower for the cold. The steady state force level, comparedwith the normal, was significantly increased under the hot condition and significantly depressed under the cold.

Force-Time Characteristics of the Exertion and Release of Hand Grip Strength under Normal and Fatigued Conditions

Abstract A recording, spring-loaded hand ergograph was used to record force-time relationships as 32 young men were tested on a hand dynamometer. Exponential equations were used to describe the changes in hand grip force during development and release. Strength reached half of its maximal value in .08 sec. and three-fourths in .15 sec. During release, the force dropped to the halfway point in .04 sec. and to the three-fourths point in .06 sec. Under conditions of fatigue the rate of buildup of muscular force decreased 50 percent, and the rate of release decreased 150 percent.

Oxygen intake curves reflecting circulatory factors in static work

SummaryOxygen consumption curves were obtained during static exercise on 34 young males. The workloads consisted of 70, 100, 130, and 160 Ibs. resistance. At the onset as well as immediately after the termination of the work period sudden changes of the normal (dynamic exercise) pattern of oxygen consumption were noted and explained in terms of circulatory factors. The linear increase in the “debt/income” ratio (oxygen intake during recovery over oxygen intake during work) with the increase in load shows that the circulation becomes increasingly impaired during static contraction. The metabolic cost of static work must be met by a relatively larger debt payoff during the recovery period.

Active and passive recovery from maximal aerobic capacity work

SummaryThirteen subjects performed two identical maximal aerobic capacity tasks on the bicycle ergometer, at one time recovering while sitting absolutely quiet and once while continuing to pedal at the same RPM against minimal resistance. The heart rate, oxygen-debt pay-off, and carbon-dioxide expulsion curves during recovery were established. Comparison of the Active and Passive recovery data showed no difference above their respective levels of return (“Zero” load pedaling or resting), except for substantially slower pay-off of the “lactic” part of the oxygen debt.

Oxygen consumption during submaximal exercises of equal intensity and different duration

SummaryTwenty-six young male subjects performed work on a bicycle ergometer at a rate of 640 mKg/min. There were two tests per subject; one used a five-minute work period and the other a ten-minute work period. Oxygen uptake curves were obtained during the work and for seven minutes of recovery. Statistical analysis showed that no true steady state was reached even at this relatively low level of work. The deficit part of the average O2 uptake curve was an almost exact mirror image of the repayment curve. The correlation between the individual deficit and pay-off values of oxygen uptake was found to be significant.

Use of Body Components as Reference Standards for Basal Metabolic Rate

Abstract Thirty-seven variables, including those representing skeletal size, lean body mass, fat mass, water content, and total mass of the body, were measured in 100 male students 18–20 years old. The relationships of the above body components to basal oxygen intake showed weight, water-free mass, and lean body mass to be better reference standards than body surface area for the comparison of basal metabolic rates.

Maximal Work Capacity of Human Intact Muscle under Hyperaemic Conditions

Abstract Fatigue curves for the forearm muscles, doing maximal static and dynamic work, were obtained under control conditions and under conditions of hyperaemia. The hyperaemia was evoked by subjecting the muscles of the forearm for a specific length of time to circulatory occlusion with a blood pressure cuff and then suddenly releasing the cuff pressure. The maximal increase in forearm volume, resulting from the postocclusion hyperaemia, followed a mathematical curve when it was expressed as a function of the occlusion time. A significant decrement in work capacity was found immediately after ten minutes of occlusion. This short-time negative influence did not affect the total output.