title: Neural Activation During Submaximal Contractions Seems More Reflective of Neuromuscular Ageing than Maximal Voluntary Activation.
abstract: This study aimed at testing the hypothesis that differences in neural activation strategy during submaximal but not maximal plantarflexions exist between young and older men. Eleven young men (YM, 26 ± 4 years) and thirteen old men (OM, 76 ± 3 years) volunteered for the investigation. Maximal voluntary torque (MVT) was 38.2%, lower (p < 0.001) in OM than in YM, while voluntary activation was equivalent (~97%). The relationship between the interpolated twitch-torque and the voluntary torque (IT-VT relationship) was composite (curvilinear + exponential) for both age-groups. However, the OM showed accentuated concavity, as attested by the occurrence of the deviation from linearity at a lower contraction intensity (OM: 54.9 vs. YM: 71.9% MVT). In conclusion, ageing does not affect the capacity to fully activate the plantar flexors during maximal performances, but it alters the activation pattern for submaximal levels of effort. The greater age-related concavity of the IT-VT relationship suggests that, during submaximal contractions, OM need to reach a level of activation higher than YM to develop an equivalent relative torque.
authors.affiliation: Université de Bourgogne Franche-Comté (UBFC), Cognition Action et Plasticité Sensorimotrice (CAPS) UMR1093Dijon, France; Institut National de la Santé et de la Recherche Médicale (INSERM U1093), Cognition Action et Plasticité Sensorimotrice (CAPS) UMR1093Dijon, France.
authors.forename: Gil
authors.initials: G
authors.lastname: Scaglioni
authors.affiliation: School of Graduate Entry to Medicine and Health, Faculty of Medicine, MRC-Arthritis Research UK Centre of Excellence for Musculoskeletal Ageing Research, University of Nottingham Derby, UK.
authors.forename: Marco V
authors.initials: MV
authors.lastname: Narici
authors.affiliation: Université de Bourgogne Franche-Comté (UBFC), Cognition Action et Plasticité Sensorimotrice (CAPS) UMR1093Dijon, France; Institut National de la Santé et de la Recherche Médicale (INSERM U1093), Cognition Action et Plasticité Sensorimotrice (CAPS) UMR1093Dijon, France.
authors.forename: Alain
authors.initials: A
authors.lastname: Martin
keywords: ageing; triceps surae; twitch interpolation; voluntary activation; voluntary contraction