P. E. di Prampero

Relationship between O2 consumption, high energy phosphates and the kinetics of the O2 debt in exercise

SummaryThe oxygen consumption together with lactic acid production and concentration of ATP, ADP, and creatinephosphate was measured during exercise and recovery on an isolated dog gastrocnemius.Oxygen debt contraction and payment follow an exponential path with a half reaction time of about 20 sec. The concentration of ATP and ADP at steady state seem to be unaffected by the intensity of the exercise when this is submaximal and no appreciable production of lactic acid takes place. The concentration of creatinephosphate in muscle at steady state decreases with the intensity of the exercise. The ratio of the oxygen consumption at steady state to the alactic oxygen debt is identified with the speed constant of the resynthesis of phosphagen in muscle; the half reaction time of this process is 17–20 sec. The total alactic oxygen debt amounts to about 50 ml/kg of muscle. These figures are in good agreement with earlier data found in man.

Maximal Muscular Power (Aerobic and Anaerobic) in African Natives

Abstract Maximal aerobic and anaerobic power have been investigated on a group of African natives (Nilo-Hamitic and Bantu) together with some anthropometric characteristics (skinfold thickness, dimension of the limbs and various body segments). These data have been compared with similar findings on other ethnic groups as obtained from the literature. It is concluded that the body fat percentage is significantly lower in African natives, particularly in children; the maximal aerobic power, when expressed per kg of fat-free body weight, is not significantly different among different ethnic groups; the maximal anaerobic power is lower in African natives, possibly because of a different anatomy and geometry of the lower limb muscles.

Maximal Muscular Power, Aerobic and Anaerobic, in II6 Athletes performing at the XlXth Olympic Games in Mexico

Maximal aerobic and anaerobic power, together with fat-free body weight, were determined by means of indirect methods on a group of L16 athletes from different countries, competing in different events, on the occasion of the Olympic Games in Mexico (2300 m above sea level). The highest absolute value in terms of maximal aerobic energy expenditure was observed in the rowers (4400 ml O2/min or 2·1 hp), while if referred to 1 kg body weight the highest value was observed in long-distance runners (65 ml O2/kg min) In terms of maximal anaerobic power, values of about 200 ml/kg min, if expressed in energy (O2) consumption, or 0·025 hp/kg, if expressed in mechanical work performed, were observed on pentathlotes and sprinters. The fat content of Olympic athletes, independent of their speciality, is significantly lower than that of ordinary people. No significant difference has been found, in terms of maximal aerobic and anaerobic power relative to fat-free body weight, between athletes and members of the ordinary...

Mechanical efficiency of phosphagen (ATP+CP) splitting and its speed of resynthesis

SummaryFrom the amount of work at steady state, and the concentration of split phosphagen, equivalent to the oxygen debt, measured on an exercising isolated dog gastrocnemius, the velocity constant of phosphagen (ATP+CP) resynthesis, assuming that this reaction is an exponential one, could be calculated and found to be 1.98 min−1, the same value as found in man in exercise.The mechanical equivalent of phosphagen splitting in man has been calculated as 4.3 kcal/mol.

Energy sour es and mechanical efficiency of anaerobic work in dog gastrocnemius

AbstractThermally isolated dog gastrocnemii were stimulated to exhaustion by rhythmic isotonic tetani of 0.2 s duration (30 min−1) in complete occlusion of blood flow. Total enthalpy change,H=heat+work, work output,w, (kJ·kg−1) and average mechanical efficiency over the working period, η=w/H, were determined from deep muscle temperature increase and amount of shortening, and lactate produced, La, (mol·kg−1) from washout curves, respectively. Under these conditionsH is the sum of the enthalpies due to a) alactic sources (Ha1), i.e., net ∼ P depletion and muscle O2 stores utilization, and b) La formation: “

O2 consumption and metabolite balance in the dog gastrocnemius at rest and during exercise

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Relationships between mechanical power, O 2 consumption, O 2 deficit and high-energy phosphates during calf exercise in humans

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