A body-fixed-sensor-based analysis of stair ascent and sit-to-stand to detect age-related differences in leg-extensor power

Abstract

Human ageing is accompanied by a progressive decline in leg-extensor power (LEP). LEP is typically measured with specialized and expensive equipment, which limits the large-scale applicability. Previously, sensor-based trunk kinematics have been used to estimate the vertical power required to elevate the body’s center of mass during functional tests, but the link with LEP and age remains to be investigated. Therefore, we investigated whether a body-fixed sensor-based analysis of power during stair ascent (SA) and sit-to-stand (STS) is positively related to LEP and whether its ability to detect age-related declines is similar. In addition, the effect of load during SA and STS was investigated. 98 adults (20–70 years) performed a leg press to assess LEP, SA and 5-repetition STS tests. In SA and STS, two conditions were tested: unloaded and loaded (+10% body mass). An inertial measurement unit was used to analyze (sub)-durations and vertical power. SA and STS power were more related to LEP than duration parameters (i.e. 0.80–0.81 for power and -0.41 –-0.66 for duration parameters, p < 0.05). The average annual age-related percent change was higher in SA power (-1.38%) than in LEP (-0.86%) and STS power (-0.38%) (p < 0.05). Age explained 29% in SA power (p < 0.001), as opposed to 14% in LEP (p < 0.001) and a non-significant 2% in STS power (p = 0.102). The addition of 10% load did not influence the age-related decline of SA and STS power nor the relationship with LEP. These results demonstrate the potential of SA tests to detect age-related deterioration in neuromuscular function. SA seems more sensitive to detect age-related changes than LEP, probably because of the additional balance component and plantar- and dorsiflexor activity. On the contrary, STS is less sensitive to age-related changes because of a ceiling effect in well-functioning adults.

Relation between leg extension power and 30-s sit-to-stand muscle power in older adults: validation and translation to functional performance

“…The time spent to complete the concentric phase of one STS repetition was calculated as half the duration of the entire test (30 s) multiplied by the total number of repetitions completed during the test (i.e. assuming that duration of the concentric and eccentric phases is similar 48 ). Mean acceleration over the concentric displacement phase was zero since initial and final velocities always were zero.…”

Reduced knee extensor torque production at low to moderate velocities in postmenopausal women with knee osteoarthritis

“…The highest mean power output (for the power variable) and the trial with the lowest total ascent duration (for the duration parameters) were used in the analyses. Excellent reliability for this method was reported, with ICCs ranging from 0.93 to 0.94 and SEM (%) from 4.0 to 6.3 16 . For the STS, the total duration (s) was determined from movement initiation until the fifth standing position.…”

An age-adapted plyometric exercise program improves dynamic strength, jump performance and functional capacity in older men either similarly or more than traditional resistance training

“…The highest mean power output was used in the analyses. For more detailed information on the calculation of power by means of 3D accelerometry, see previous work [28].…”

“…Higher levels of muscle power can at least postpone the drop below the disability threshold. Secondly, STS ability is subject to a ceiling effect in well-functioning adults, as noted previously [28]. Instead of questioning the beneficial effect of plyometric exercise on functional performance, it may be necessary to question whether traditional functional performance tests are sensitive enough to capture changes in well-functioning older adults.…”