Influence of fatigue and velocity on the latency and recruitment order of scapular muscles

Abstract

The simultaneous presence of fatigue and high-velocity in an arm raise task is associated with a decrease in the UT activation latency and a modification of the recruitment order of scapular muscles.

Relationship between anthropometric and electromyographic variables of the scapular muscles

“…This is because the greater fat content around the muscle has a close relationship with the infiltration of fat in the muscle fibres [5], which favours inflammation and impairs muscular mechanical efficiency [31,32]. in turn, fatigue affects motor control and the order of recruitment of the scapular muscles during an arm raise task [17]. Therefore, it is important to know the muscle performance prior to the EMG evaluation, since fatigue affects the onset latency and muscle recruitment order.…”

“…in this context, there are no studies that evaluate the influence of adipose tissue accumulation on the onset latency, especially of muscles that are part of the axial skeleton. The variation of latency is an important indicator of neuromuscular control, as it allows estimation of the recruitment order of the muscles that stabilize and mobilize a joint [16][17][18]. in this sense, it is important to understand the relationship between skinfolds and the onset latency of the scapular muscles, as if there is a relationship, this would be a determining factor when evaluating, analysing, and interpreting the surface EMG record.…”

Influence of adiposity and fatigue on the scapular muscle recruitment order

“…A total sample of 34 voluntary participants (17 participants per group: no-fatigue and fatigue) was calculated based on a 95% confidence interval, a power of 0.9, and an expected 15% loss. For this calculation, SA onset latency reported in a previous study was used (Mendez-Rebolledo et al., 2018a), where a mean difference of 53.3 ms and a standard deviation of 38.4 ms was observed in the no-fatigue condition and 55.1 ms was observed in the fatigue condition. Participants between 18 and 24 years of age were included.…”

“…In young adults, overweight and obesity lead to a decrease in force control and an increase in fatigue (Mehta, 2015; Mehta & Shortz, 2014). In addition, an alteration in the activation pattern of the scapular stabilizing muscles, in non-obese subjects has been observed, as reflected in the delayed activation of the scapular muscles under fatigue conditions (Cools et al, 2002; Mendez-Rebolledo et al., 2018a). However, there are no reports regarding the effect of excess body weight on the muscle activation pattern.…”

“…Neuromuscular parameters that are frequently studied are signal amplitude, conduction velocity, fatigability, frequencies, and onset latency (Hug, 2011; Struyf et al, 2014). In the scapular muscles, the onset latency corresponds to the time between the EMG activation of a scapular muscle and the activation of the anterior deltoid (primary motor muscle) (Mendez-Rebolledo et al., 2018a; Phadke & Ludewig, 2013), which determines the muscle recruitment order during voluntary motor tasks. Several authors have indicated that excess body weight can reduce the EMG amplitude due to the accumulation of fat in the layers of tissue that separate the muscle from the skin (Cooper et al, 2014; De Vito et al., 2003; Phadke & Ludewig, 2013).…”