Carbohydrate metabolism and electrolyte changes in human muscle tissue during heavy work.

Bergström, Jonas; Guarnieri, Giulia; Hultman, E.

doi:10.1152/jappl.1971.30.1.122

Cited by 109 publications

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“…As expected, the exercise-and electrolyte administration-induced changes in [Na ϩ ] and [Cl Ϫ ] were seen in the extracellular (plasma) compartment (57), while the estimated 1% decrease in total body K ϩ was not sufficient to alter muscle [K ϩ ] or content. In contrast, a decreased skeletal muscle K ϩ content and an increased Na ϩ content occur during moderate-to high-intensity exercise in men (5,10,51). A possible explanation for the maintenance of muscle K ϩ at 0 h of recovery (ϳ20 min postexercise) in the present study is that any sweat losses were countered by the high rates of Na Studies on electrolyte contents of equine muscle are rare; however, resting values for K ϩ and Mg 2ϩ contents in the present study are similar to those found previously in horses using flame photometer or atomic absorption spectrometry (AAS) (38) or X-ray microanalysis (19), whereas Na ϩ and Cl Ϫ contents are somewhat lower than in previous studies (Na ϩ ϳ10 -20 meq/kg wet wt, Cl Ϫ ϳ30 meq/kg wet wt) (19,38).…”

Section: Discussionmentioning

confidence: 87%

Fluid and electrolyte supplementation after prolonged moderate-intensity exercise enhances muscle glycogen resynthesis in Standardbred horses

Waller¹,

Heigenhauser²,

Geor³

et al. 2009

Journal of Applied Physiology

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Waller AP, Heigenhauser GJ, Geor RJ, Spriet LL, Lindinger MI. Fluid and electrolyte supplementation after prolonged moderateintensity exercise enhances muscle glycogen resynthesis in Standardbred horses. J Appl Physiol 106: 91-100, 2009. First published October 23, 2008 doi:10.1152/japplphysiol.90783.2008.-We hypothesized that postexercise rehydration using a hypotonic electrolyte solution will increase the rate of recovery of whole body hydration, and that this is associated with increased muscle glycogen and electrolyte recovery in horses. Gluteus medius biopsies and jugular venous blood were sampled from six exercise-conditioned Standardbreds on two separate occasions, at rest and for 24 h following a competitive exercise test (CET) designed to simulate the speed and endurance test of a 3-day event. After the CETs, horses were given water ad libitum, and either a hypotonic commercial electrolyte solution (electrolyte) via nasogastric tube, followed by a typical hay/grain meal, or a hay/grain meal alone (control). The CET resulted in decreased total body water and muscle glycogen concentration of 8.4 Ϯ 0.3 liters and 22.6%, respectively, in the control treatment, and 8.2 Ϯ 0.4 liters and 21.9% in the electrolyte treatment. Electrolyte resulted in an enhanced rate of muscle glycogen resynthesis and faster restoration of hydration (as evidenced by faster recovery of plasma protein concentration, maintenance of plasma osmolality, and greater muscle intracellular fluid volume) during the recovery period compared with control. There were no differences in muscle Na, K, Cl, or Mg contents between the two treatments. It is concluded that oral administration of a hypotonic electrolyte solution after prolonged moderate-intensity exercise enhanced the rate of muscle glycogen resynthesis during the recovery period compared with control. It is speculated that postexercise dehydration may be one key contributor to the slow muscle glycogen replenishment in horses. skeletal muscle; rehydration; exercise; instrumental neutron activation analysis IN THE HORSE, BOTH short-term, high-intensity, and prolonged submaximal exercise result in dehydration, loss of water and electrolytes, and depletion of skeletal muscle glycogen (23,30,31,52,53,56). Resynthesis of muscle glycogen stores requires 48 -72 h in horses, compared with 2.5 h in rats (16) and Ͻ24 h in humans (12). Previous studies in horses have altered postexercise nutrition strategies in attempts to enhance muscle glycogen resynthesis. Despite demonstrations that intravenous infusion of large amounts of glucose (3-6 g/kg) modestly accelerated muscle glycogen replenishment (14, 17), conventional feeding strategies have not been successful (23,(53)(54)(55). Initial glycogen resynthesis rates in horses after ingestion of meals with varying soluble carbohydrate (CHO) contents ranged from ϳ8 to ϳ12 mmol⅐kg dry wt Ϫ1 ⅐h Ϫ1 for mixed and high-soluble CHO diets, respectively. In contrast, in humans, initial glycogen storage rates are ϳ40 mmol⅐kg dry wt Ϫ1 ⅐h Ϫ1when at least 5 g/kg...

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Section: Discussionmentioning

confidence: 87%

Fluid and electrolyte supplementation after prolonged moderate-intensity exercise enhances muscle glycogen resynthesis in Standardbred horses

Waller¹,

Heigenhauser²,

Geor³

et al. 2009

Journal of Applied Physiology

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“…Although, we could find no evidence for a greater impairment in neuromuscular function during submaximal exercise in hypoxia, such may not be the case with progressive exercise. In contrast to submaximal exercise where force levels and motor unit firing rates are relatively low and V O 2 and muscle energy homeostasis are well protected (24,50), the generation of increased forces needed to perform progressive exercise exaggerates the demands on membrane excitability and V O 2 requirements and, in the process, greatly elevates metabolic by-product accumulation in muscle (6,49).…”

mentioning

confidence: 99%

Muscle Na-K-pump and fatigue responses to progressive exercise in normoxia and hypoxia

Sandiford

Green

Duhamel

et al. 2005

American Journal of Physiology-Regulatory, Integrative and Comp

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To investigate the effects of hypoxia and incremental exercise on muscle contractility, membrane excitability, and maximal Na+-K+-ATPase activity, 10 untrained volunteers (age = 20 ± 0.37 yr and weight = 80.0 ± 3.54 kg; ± SE) performed progressive cycle exercise to fatigue on two occasions: while breathing normal room air (Norm; FiO2 = 0.21) and while breathing a normobaric hypoxic gas mixture (Hypox; FiO2 = 0.14). Muscle samples extracted from the vastus lateralis before exercise and at fatigue were analyzed for maximal Na+-K+-ATPase (K+-stimulated 3-O-methylfluorescein phosphatase) activity in homogenates. A 32% reduction ( P < 0.05) in Na+-K+-ATPase activity was observed (90.9 ± 7.6 vs. 62.1 ± 6.4 nmol·mg protein−1·h−1) in Norm. At fatigue, the reductions in Hypox were not different (81 ± 5.6 vs. 57.2 ± 7.5 nmol·mg protein−1·h−1) from Norm. Measurement of quadriceps neuromuscular function, assessed before and after exercise, indicated a generalized reduction ( P < 0.05) in maximal voluntary contractile force (MVC) and in force elicited at all frequencies of stimulation (10, 20, 30, 50, and 100 Hz). In general, no differences were observed between Norm and Hypox. The properties of the compound action potential, amplitude, duration, and area, which represent the electomyographic response to a single, supramaximal stimulus, were not altered by exercise or oxygen condition when assessed both during and after the progressive cycle task. Progressive exercise, conducted in Hypox, results in an inhibition of Na+-K+-ATPase activity and reductions in MVC and force at different frequencies of stimulation; these results are not different from those observed with Norm. These changes occur in the absence of reductions in neuromuscular excitability.

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“…The water content in the inactive muscle was slightly decreased at the same time. Bergstrom et al (2) also found that heavy exercise caused water accumulation in active muscles, accompanied by lactate accumulation. It was suggested that the accumulation of water in active muscles was related to the increased osmolality caused by the production of lactate.…”

Section: Fluid Shift and Electrolyte Loss During Exercisementioning

confidence: 96%

“…In a study, muscle glycogen levels were found depleted after exercise at 1000 kpm/min for 20 min (2,45). One of the subjects in the study was not able to finish 20 min of exercise and terminated exercise at 17 min of exercise.…”

Section: Plasma Glucose and Muscle Glycogenmentioning

confidence: 97%

See 1 more Smart Citation

The Effect Of Sodium And Carbohydrate In A Rehydration Food On Subsequent Exercise Performance

Yan

2009

Medicine &Amp; Science in Sports &Amp; Exercise

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Carbohydrate metabolism and electrolyte changes in human muscle tissue during heavy work.

Cited by 109 publications

References 0 publications

Fluid and electrolyte supplementation after prolonged moderate-intensity exercise enhances muscle glycogen resynthesis in Standardbred horses

Fluid and electrolyte supplementation after prolonged moderate-intensity exercise enhances muscle glycogen resynthesis in Standardbred horses

Muscle Na-K-pump and fatigue responses to progressive exercise in normoxia and hypoxia

The Effect Of Sodium And Carbohydrate In A Rehydration Food On Subsequent Exercise Performance

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