Skeletal muscle buffering capacity is higher in the superficial vastus than in the soleus of spontaneously running rats

Weston, Adèle R.; Wilson, GR; Noakes, Timothy D.; Myburgh, K. H.

doi:10.1046/j.1365-201x.1996.488225000.x

Cited by 20 publications

(18 citation statements)

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“…This value was then normalised to the whole pH unit for final display as millimoles H + per gram dry muscle per unit pH and determined as the subject's bm in vitro . The coefficient of variation for the measurement of bm in vitro using this technique in our laboratory is 5.4% and is comparable to that reported elsewhere (Weston et al 1996).…”

Section: Muscle Buffering Capacity; Titration Methods (Bm In Vitro )supporting

confidence: 79%

Muscle buffer capacity and aerobic fitness are associated with repeated-sprint ability in women

2004

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In addition to a high aerobic fitness, the ability to buffer hydrogen ions (H+) may also be important for repeated-sprint ability (RSA). We therefore investigated the relationship between muscle buffer capacity (betamin vivo and betamin vitro) and RSA. Thirty-four untrained females [mean (SD): age 19 (1) years, maximum oxygen uptake (VO2peak) 42.3 (7.1) ml x kg(-1) x min(-1)] completed a graded exercise test (GXT), followed by a RSA cycle test (five 6-s sprints, every 30 s). Capillary blood was sampled during the GXT and before and after the RSA test to determine blood pH (pHb) and lactate concentration ([La-]b). Muscle biopsies were taken before (n=34) and after (n=23) the RSA test to determine muscle lactate concentration ([La-]i), hydrogen ion concentration ([H+]i) pHi, betamin vivo and betamin vitro. There were significant correlations between work decrement (%) and betamin vivo (r=-0.72, P<0.05), VO2peak (r=-0.62, P<0.05), lactate threshold (LT) (r=-0.56, P<0.05) and changes in [H+]i (r=0.41, P<0.05). There were however, no significant correlations between work decrement and betamin vitro, or changes in [La-]i, or [La-]b. There were also no significant correlations between total work (J x kg(-1)) during the RSA test and betamin vitro, betamin vivo, or changes in [La-]i, pHi, [La-]b, or pHb. There were significant correlations between total work (J x kg(-1)) and both VO2peak (r=0.60, P<0.05) and LT(r=0.54, P<0.05). These results support previous research, identifying a relationship between RSA and aerobic fitness. This study is the first to identify a relationship between betamin vivo and RSA. This suggests that the ability to buffer H+ may be important for maintaining performance during brief, repeated sprints.

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Section: Muscle Buffering Capacity; Titration Methods (Bm In Vitro )supporting

confidence: 79%

Muscle buffer capacity and aerobic fitness are associated with repeated-sprint ability in women

2004

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“…A fall in pH is known to inhibit skeletal muscle contractility (Donaldson et al 1978;Fabiato and Fabiato 1978;Cooke et al 1988). An alternative explanation for this finding is that those subjects with better time trial performances had a higher percentage of fast-twitch fibres than the somewhat slower cyclists, since m has been correlated with the percentage cross-sectional area occupied by type-II fibres (Mannion et al 1995) and type-II fibres have been shown to have a higher m than type-I fibres (Weston et al 1996). However, we are unable to explain why m was not related to a supramaximal test lasting approximately 1 min (TF 150 ).…”

Section: Discussionmentioning

confidence: 94%

“…Homogenates were titrated from pH 7.1 and 6.5 as this was considered representative of muscle pH from rest to exhaustion during intense exercise. The coefficient of variation for the measurement of m titr using this technique in this laboratory is ± 3.0% (Weston et al 1996) and is comparable to that reported elsewhere (Mannion et al 1993). Results are expressed per full pH unit for final expression as mol H + · g muscle dw -1 · pH -1 .…”

Section: Buffering Capacity ( M)mentioning

confidence: 89%

Skeletal muscle buffering capacity and endurance performance after high-intensity interval training by well-trained cyclists

Weston¹,

Myburgh²,

Lindsay³

et al. 1996

European Journal of Applied Physiology

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218

182

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Skeletal muscle buffering capacity (beta m), enzyme activities and exercise performance were measured before and after 4 weeks of high-intensity, submaximal interval training (HIT) undertaken by six well-trained competitive cyclists [mean maximal oxygen consumption (VO2max) = 66.2 ml.kg-1.min-1]. HIT replaced a portion of habitual endurance training and consisted of six sessions, each of six to eight repetitions of 5 min duration at 80% of peak sustained power output (PPO) separated by 1 min of recovery. beta m increased from 206.6 (17.9) to 240.4 (34.1) mumol H+.g muscle dw-1.pH-1 after HIT (P = 0.05). PPO, time to fatigue at 150% PPO (TF150) and 40-km cycle time trial performance (TT40) all significantly improved after HIT (P < 0.05). In contrast, there was no change in the activity of either phosphofructokinase or citrate synthase. In addition, beta m correlated significantly with TT40 performance before HIT (r = -0.82, P < 0.05) and the relationship between change in beta m and change in TT40 was close to significance (r = -0.74). beta m did not correlate with TF150. These results indicate that beta m may be an important determinant of relatively short-duration (< 60 min) endurance cycling activity and responds positively to just six sessions of high-intensity, submaximal interval training.

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“…Several groups have found that sprint performances are related to percentage of type II fibres [56][57][58][59] and that percentage of type II fibres correlates with β m in men [44,52,60,61] and in rats. [62] More reliable, longitudinal studies [35,[63][64][65] have shown that sprint training either increased or had no effect on β m in previously untrained individuals (table V), but improved power output. Sprint training was also found to have no influence on two muscle metabolites that contribute to β m ( [66][67][68] and humans.…”

Section: Effects Of High-intensity Sprint Training In Previously Untrmentioning

confidence: 99%

Training Techniques to Improve Endurance Exercise Performances

2002

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In previously untrained individuals, endurance training improves peak oxygen uptake (V. O2peak), increases capillary density of working muscle, raises blood volume and decreases heart rate during exercise at the same absolute intensity. In contrast, sprint training has a greater effect on muscle glyco(geno)lytic capacity than on muscle mitochondrial content. Sprint training invariably raises the activity of one or more of the muscle glyco(geno)lytic or related enzymes and enhances sarcolemmal lactate transport capacity. Some groups have also reported that sprint training transforms muscle fibre types, but these data are conflicting and not supported by any consistent alteration in sarcoplasmic reticulum Ca 2+ ATPase activity or muscle physicochemical H + buffering capacity. While the adaptations to training have been studied extensively in previously sedentary individuals, far less is known about the responses to high-intensity interval training (HIT) in already highly trained athletes. Only one group has systematically studied the reported benefits of HIT before competition. They found that ≥6 HIT sessions, was sufficient to maximally increase peak work rate (Wpeak) values and simulated 40km time-trial (TT40) speeds of competitive cyclists by 4 to 5% and 3.0 to 3.5%, respectively. Maximum 3.0 to 3.5% improvements in TT40 cycle rides at 75 to 80% of Wpeak after HIT consisting of 4-to 5-minute rides at 80 to 85% of Wpeak supported the idea that athletes should train for competition at exercise intensities specific to their event. The optimum reduction or 'taper' in intense training to recover from exhaustive exercise before a competition is poorly understood. Most studies have shown that 20 to 80% single-step reductions in training volume over 1 to 4 weeks have little effect on exercise performance, and that it is more important to maintain training intensity than training volume. Progressive 30 to 75% reductions in pool training volume over 2 to 4 weeks have been shown to improve swimming performances by 2 to 3%. Equally rapid exponential tapers improved 5km running times by up to 6%. We found that a 50% single-step reduction in HIT at 70% of Wpeak produced peak ~6% improvements in simulated 100km time-trial performances after 2 weeks. It is possible that the optimum taper depends on the intensity of the athletes'preceding training and their need to recover from exhaustive exercise to compete. How the optimum LEADING ARTICLE

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Skeletal muscle buffering capacity is higher in the superficial vastus than in the soleus of spontaneously running rats

Cited by 20 publications

References 0 publications

Muscle buffer capacity and aerobic fitness are associated with repeated-sprint ability in women

Muscle buffer capacity and aerobic fitness are associated with repeated-sprint ability in women

Skeletal muscle buffering capacity and endurance performance after high-intensity interval training by well-trained cyclists

Training Techniques to Improve Endurance Exercise Performances

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