Effect of temperature on muscle energy metabolism and endurance during successive isometric contractions, sustained to fatigue, of the quadriceps muscle in man

Abstract

SUBMARY1. The effects of altered tissue temperature on muscle metabolism during successive isometric contractions, sustained to fatigue, have been studied in the quadriceps muscle of man by combining biochemical analyses of metabolites in needle biopsy samples with measurements of endurance time with a force of 2/3 maximum voluntary contraction. Fatigue and recovery were observed repeatedly in a series of seven contractions at intervals of 20 sec, following immersion of the test leg in water at 12, 26 or 440 C for 45 min. Muscle temperatures corresponding to these water temperatures were 22-5, 32-6 and 38 6°C respectively.2. Increased levels of several glycolytic intermediates at rest in the heated muscle suggested an increased rate of glycolysis. ATP and phosphoryl creatine were lower at the end of the first contraction and the calculated rate of ATP utilization (including the contribution from anaerobic glycolysis) was highest in the heated nuscle.3. Significantly shorter endurance times were found for the heated muscle. These could not be attributed to depletion of local energy resources in muscle. Fatigue may be due to a reduction in the rate of regeneration of ATP from anaerobic glycolysis below that needed to maintain the contraction force. Lower values for the ratio of fructose 1,6-diphosphate: fructose 6-phosphate at the end of contractions, particularly at the highest temperature, are compatible with the hypothesis that there is partial inhibition of the rate controlling enzyme phosphofructokinase, possibly due to the accumulation of hydrogen ions in muscle.

External muscle heating during warm-up does not provide added performance benefit above external heating in the recovery period alone

“…It is well established that muscle temperature (T m ) has a significant effect on muscle function, force and power production (Asmussen and Boje 1945;Bergh and Ekblom 1979;De Ruiter and De Haan 2000;Edwards et al 1972;Racinais et al 2005;Sargeant 1987). Much of the available literature suggests that events that require high levels of power production tend to benefit from increases in muscle temperature (Asmussen and Boje 1945;Hajoglou et al 2005).…”

Dissociation between metabolic and contractile responses during intermittent isometric exercise in man

“…Fatigue during isometric contraction in human muscle has generally been associated with ischaemia, leading to rapid phosphocreatine (PCr) depletion and accumulation of metabolites (Ahlborg, Bergstrom, Ekelund, Guarnieri, Harris, Hultman & Nordesjo, 1972;Edwards, Harris, Hultman & Nordesjo, 1972a;Sahlin, Harris & Hultman, 1975;Harris, Sahlin & Hultman, 1977). Within this protocol, fatigue, defined as a decline in maximal force (BiglandRitchie, Furbush & Woods, 1986b;V0llestad, Sejersted, Bahr, Woods & Bigland-Ritchie, 1988) is explained at the cellular level, where the inhibiting effect of high inorganic phosphate (Pi) and H' levels on maximal Ca2+-activated force is well documented (reviewed by Westerblad, Lee, Liinnergren & Allen, 1991;Fitts, 1994).…”

The effect of exercise induced hyperthermia on muscle fibre conduction velocity during sustained isometric contraction

“…This increase in lactate accumulation is 4 therefore likely to be from an increase in production without any concomitant 5 elevation in lactate clearance (Gonzalez-Alonso et al, 1999a). Generally, 6 previous studies (Edwards et al, 1972;Febbraio et al, 1996) …”

“…As a result of exercising in the heat during the HOT it is likely that there was an 2 increase in muscle metabolism (Edwards et al, 1972;Febbraio et al, 1996) as is 3 evident from the higher lactate values. This increase in lactate accumulation is 4 therefore likely to be from an increase in production without any concomitant 5 elevation in lactate clearance (Gonzalez-Alonso et al, 1999a).…”