Flexibility in joint coordination remains unaffected by force and balance demands in young and old adults during simple sit-to-stand tasks

Christian Greve,Raoul M Bongers,Tibor Hortobágyi

doi:10.1007/s00421-018-4035-4

Christian Greve, Raoul M Bongers + Show 1 more

Open Access

https://doi.org/10.1007/s00421-018-4035-4

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Abstract

PurposeWe examined the possibility that old adults use flexibility in joint coordination as a compensatory mechanism for the age-related decline in muscle strength when performing the sit-to-stand (STS) task repeatedly under high force and balance demands.MethodYoung (n = 14, 22.4 ± 2.1) and old (n = 12, 70 ± 3.2) healthy adults performed repeated STSs under high and low force and balance demands. The balance demand was manipulated by reducing the base of support and the force demand by increasing body weight with a weight vest. Uncontrolled manifold analysis was used to quantify age differences in motor flexibility.ResultsWhile there were age-typical differences in kinematic STS strategies, flexibility in joint coordination was independent of age and task difficulty during repeated STSs.DiscussionThat simple manipulations of force and balance demands did not affect flexibility in joint coordination in old and young adults suggests that motor flexibility acts as a compensatory mechanism only at the limits of available muscle strength and balance abilities during STS movements. Intervention studies should identify how changes in specific neuromuscular functions affect flexibility in joint coordination during activities of daily living such as STS.

Highlights

Communicated by Toshio Moritani.Standing up from a chair or bed is a frequent activity of daily living and requires muscle strength, power, and balance (Dall and Kerr 2010; Hughes et al 1994, 1996; Riley et al 1991)
In line with this idea we found in a previous study that old adults, as compared to young adults, increase co-variation among the lower- and upper-extremity joints, the trunk and the neck to improve center of mass (COM) stability at lift-off when repeatedly performing the same STS task (Greve et al 2013)
Old compared with young adults had less peak knee extensor and knee flexor muscle strength but represented good balance and overall physical performance capacities

Summary

Introduction

Communicated by Toshio Moritani.Standing up from a chair or bed is a frequent activity of daily living and requires muscle strength, power, and balance (Dall and Kerr 2010; Hughes et al 1994, 1996; Riley et al 1991). In compensation for the age-related decline in neuromuscular function, old adults compared with young adults adjust their movement patterns and execute the sit-tostand (STS) tasks more slowly, with a greater trunk flexion, and with lower peak vertical ground reaction forces at lift-off (Alexander et al 2001; Gross et al 1998; Hughes et al 1994, 1996; Yamada and Demura 2010). During task execution old and young adults make use of this abundance in the movement repertoire and adapt the STS movement to external (e.g., chair height), and internal (e.g., muscle weakness, instability) constraints (Newell 1986; Hu and Newell 2011) through small and coordinated adjustments among all available joint motions This flexibility in joint coordination underlies multi-joint co-variation and guarantees safe COM positions during daily-life STS performance where the actual constraints to movement are poorly predictable, and might even change. This concept of performance stability through flexibility in joint coordination has been previously described and tested in STS and other motor tasks (Domkin et al 2002; Eckardt and Rosenblatt 2018; Golenia et al 2018; Greve et al 2013; Latash 2012; Latash et al 2007; Olafsdottir et al 2007; Scholz and Schöner 1999; Wu et al 2013)

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