Oxygen supply/uptake mismatch during incremental stimulation of the human tibialis anterior
Tóm tắt
Local oxygen supply/uptake mismatch (O2M) of active muscles may be influenced by the effectiveness of microvascular adaptations to metabolic demand. The aim of this work was to provide a novel, objective method to measure O2M through incremental stimulation. The tibialis anterior of 20 subjects was electrically stimulated at the main motor point. The stimulation protocol involved five single twitches at maximal stimulus amplitude (Vmax = full motor unit recruitment) and five 90-s steps with increasing amplitude and frequency of the intermittent stimulation. Changes in force, oxygenated Hb (O2Hb) and deoxygenated Hb (HHb) were recorded. Contraction time (CT) of single twitches, fatigue index (FI) and O2M were calculated. F-statistics identified two groups of muscles, one with FI < 0.69 (group F, more fatiguable) and one with FI > 0.69 (group R, less fatiguable). Group R showed significantly lower CT, higher basal O2Hb, lower ΔHHb and lower O2M with respect to group F. On the basis of the relationship between O2M and FI, the proposed method distinguished two different functional capacities of human TA muscles. This tool could be applied to estimate the kinetics of aerobic adaptation to increasing metabolic demand in muscles affected by myopathies or subjected to rehabilitation or training programmes.
Tài liệu tham khảo
Boone J, Coppo K, Barstow TJ, Bouckaert J (2009) Pattern of deoxy[Hb+Mb] during ramp cycle exercise: influence of aerobic fitness status. Eur J Appl Physiol 105:851–859
Adami A, Pogliaghi S, De Roia G, Capelli C (2011) Oxygen uptake, cardiac output and muscle deoxygenation at the onset of moderate and supramaximal exercise in humans. Eur J Appl Physiol 111:1517–1527
Flück M (2006) Functional, structural and molecular plasticity of mammalian skeletal muscle in response to exercise stimuli. J Exp Biol 209:2239–2248
Bruton A (2002) Muscle plasticity: response to training and detraining. Physiotherapy 88(7):398–408
Konopka AR, Douglass MD, Kaminsky LA et al. (2010) Molecular adaptations to aerobic exercise training in skeletal muscle of older women. J Gerontol A Biol Sci Med Sci 65(11):1201–1207
Mancini DM, Bolinger L, Li H et al. (1994) Validation of near-infrared spectroscopy in humans. J Appl Physiol 77(6):2740–2747
Ferrari M, Muthalib M, Quaresima V (2011) The use of near-infrared spectroscopy in understanding skeletal muscle physiology: recent developments. Philos Transact A Math Phys Eng Sci 369(1955):4577–4590
Ferreira LF, Lutjemeier BJ, Townsed DK, Barstow TJ (2005) Dynamics of skeletal muscle oxygenation during sequential bouts of moderate exercise. Exp Physiol 90:393–401
Gobbo M, Gaffurini P, Bissolotti L et al. (2011) Transcutaneous neuromuscular electrical stimulation: influence of electrode positioning and stimulus amplitude settings on muscle response. Eur J Appl Physiol 111(10):2451–2459
Orizio C, Gobbo M, Diemont B, Solomonow M (2007) Force dynamic response of tibialis anterior-ankle joint unit in humans. J Electromyogr Kinesiol 17(2):194–202
Mesin L, Merlo E, Merletti R, Orizio C (2010) Investigation of motor unit recruitment during stimulated contractions of tibialis anterior muscle. J Electromyogr Kinesiol 20(4):580–589
Orizio C, Gobbo M, Diemont B (2004) Changes of the force-frequency relationship in human tibialis anterior at fatigue. J Electromyogr Kinesiol 14(5):523–530
Bellemare F, Woods JJ, Johansson R, Bigland-Ritchie B (1983) Motor-unit discharge rates in maximal voluntary contractions of three human muscles. J Neurophysiol 50(6):1380–1392
Burke RE (1981) Motor units: anatomy, physiology and functional organization. In: Brooks VB (ed) Handbook of physiology, Section 1: The nervous system, vol. 1, part 1. American Physiological Society, Bethesda, MD, pp 345–422
Grassi B (2006) Oxygen uptake kinetics: Why are they so slow? And what do they tell us? J Physiol Pharmacol 57(Suppl 10):53–65
Grassi B, Quaresima V, Marconi C et al. (1999) Blood lactate accumulation and muscle deoxygenation during incremental exercise. J Appl Physiol 87(1):348–355
Thompson LV, Balog EM, Riley DA, Fitts RH (1992) Muscle fatigue in frog semitendinosus: alterations in contractile function. Am J Physiol 262(6 Pt 1):C1500–C1506