). In the exercise domain, studies have measured muscle activation (i.e., motor unit activation) while performing isometric muscle contractions ( Bray et al., 2008 ; Graham, Sonne, & Bray, 2014 ) and endurance cycling ( Pageaux, Marcora, Rozand, & Lepers, 2015 ). These studies have shown that
Denver M.Y. Brown and Steven R. Bray
Lilian F. Wallerstein, Renato Barroso, Valmor Tricoli, Marco T. Mello and Carlos Ugrinowitsch
Ramp isometric contractions determine peak torque (PT) and neuromuscular activation (NA), and ballistic contractions can be used to evaluate rate of torque development (RTD) and electrical mechanical delay (EMD). The purposes of this study were to assess the number of sessions required to stabilize ramp and ballistic PT and to compare PT and NA between contractions in older adults. Thirty-five older men and women (age 63.7 ± 3.7 yr, body mass 64.3 ± 10.7 kg, height 159.2 ± 6.6 cm) performed 4 sessions of unilateral ramp and ballistic isometric knee extension, 48 hr apart. PT significantly increased (main time effect p < .05) from the first to the third session, with no further improvements thereafter. There was a trend toward higher PT in ballistic than in ramp contractions. No difference between contraction types on EMG values was observed. Therefore, the authors suggest that 3 familiarization sessions be performed to correctly assess PT. In addition, PT, NA, RTD, and EMD can be assessed with ballistic contraction in older adults.
Astrid C.J. Balemans, Han Houdijk, Gilbert R. Koelewijn, Marjolein Piek, Frank Tubbing, Anne Visser-Meily and Olaf Verschuren
muscle activation (during these postures) in the large muscle groups is associated with insulin resistance, increased triglycerides levels, and suppression of high density lipoprotein cholesterol levels 7 , 8 and is, therefore, an important aspect in SB and its association with declined health. So, not
Sangeetha Madhavan, Sarah Burkart, Gail Baggett, Katie Nelson, Trina Teckenburg, Mike Zwanziger and Richard K. Shields
Neuromuscular control strategies might change with age and predispose the elderly to knee-joint injury. The purposes of this study were to determine whether long latency responses (LLRs), muscle-activation patterns, and movement accuracy differ between the young and elderly during a novel single-limb-squat (SLS) task. Ten young and 10 elderly participants performed a series of resistive SLSs (~0–30°) while matching a computer-generated sinusoidal target. The SLS device provided a 16% body-weight resistance to knee movement. Both young and elderly showed significant overshoot error when the knee was perturbed (p < .05). Accuracy of the tracking task was similar between the young and elderly (p = .34), but the elderly required more muscle activity than the younger participants (p < .05). The elderly group had larger LLRs than the younger group (p < .05). These results support the hypothesis that neuromuscular control of the knee changes with age and might contribute to injury.
Hwang-Jae Lee, Won Hyuk Chang, Sun Hee Hwang, Byung-Ok Choi, Gyu-Ha Ryu and Yun-Hee Kim
The purpose of this study was to examine age-related gait characteristics and their associations with balance function in older adults. A total of 51 adult volunteers participated. All subjects underwent locomotion analysis using a 3D motion analysis and 12-channel dynamic electromyography system. Dynamic balance function was assessed by the Berg Balance Scale. Older adults showed a higher level of muscle activation than young adults, and there were significant positive correlations between increased age and activation of the trunk and thigh muscles in the stance and swing phase of the gait cycle. In particular, back extensor muscle activity was mostly correlated with the dynamic balance in older adults. Thus, back extensor muscle activity in walking may provide a clue for higher falling risk in older adults. This study demonstrates that the back extensor muscles play very important roles with potential for rehabilitation training to improve balance and gait in older adults.
Christopher A. Bailey, Maxana Weiss and Julie N. Côté
et al. ( 2008 ) identified lower muscle activation variability during repeated shoulder movements in workers with chronic N/S pain compared to healthy controls, suggesting a link between low variability and chronic pain. Changes in the functional connectivity between pairs of muscles have also been
Lauren J. Lattimer, Joel L. Lanovaz, Jonathan P. Farthing, Stéphanie Madill, Soo Kim, Stephen Robinovitch and Cathy Arnold
( Feldman & Robinovitch, 2007 ; Hsiao & Robinovitch, 1998 ). Ineffective UE responses to control forward landing and descent in older adults could be attributed to a number of factors including the response time, muscle activation, strength, range of motion, or ability to absorb the force of impact and
Harsh H. Buddhadev and Philip E. Martin
position of participants because posture is known to affect energy cost ( Nordeen-Snyder, 1977 ), joint ranges of motion, and muscle activation patterns ( Sanderson & Amoroso, 2009 ). Seat height, defined as the distance from the top of the saddle to the top pedal surface along the line of the seat tube
Tijs Delabastita, Stijn Bogaerts and Benedicte Vanwanseele
. Antagonistic activation Was antagonistic muscle activation taken into account in the Achilles tendon force calculations? 6. Synergistic activation Was muscle activation of different plantar flexor muscles taken into account in the Achilles tendon force calculations? 7. Moment arm measured Was the plantar
Daniël M. van Leeuwen, Fabian van de Bunt, Cornelis J. de Ruiter, Natasja M. van Schoor, Dorly J.H. Deeg and Kaj S. Emanuel
Rheumatology, 20 ( 1 ), 3 – 25 . PubMed doi:10.1016/j.berh.2005.09.007 10.1016/j.berh.2005.09.007 Brandon , S.C.E. , Miller , R.H. , Thelen , D.G. , & Deluzio , K.J. ( 2014 ). Selective lateral muscle activation in moderate medial knee osteoarthritis subjects does not unload medial knee condyle