Field evaluation of cycled coupled movements of hand and foot in older individuals

Age-related deterioration of motor performance has been investigated, often associated to behavioral slowing and to modification in the quality of movement coordination. However, the complexity of laboratory settings restrains sound quantitative evaluation of inter-limb coordination in large-scale clinical assessments, and no information regarding test stability has been provided.

The aims of the present study were to verify in homolateral hand and foot coordination field performances: (1) acceptable test-retest reliability criteria for older adults, and (2) the effects of coordination mode and test velocity at different ages across lifespan.

Seventy-seven individuals, ranging in age from 10 to 87 years, performed simultaneous flexions and extensions of the homolateral wrist and ankle in the sagittal plane with a 1:1 ratio. Two homolateral conditions (preferred and non-preferred limbs) were tested in two coordination modes: in-phase (isodirectional) and anti-phase (nonisodirectional) at three test frequencies (80, 120 and 180 bpm, respectively). Time of correct execution within a maximum of 60 s was recorded for each test condition. Older adults (n = 36) performed the test and the retest with a week interval.

High ICCs (range 0.72-0.98) and acceptable limits of agreement were found for the subsample of older adults. Main effects and significant interactions were found for age, coordination mode, and execution frequency. Time of correct execution was longest in younger adults and shortest in older individuals. At all ages, it was longer for the in-phase than in the anti-phase condition and decreased with increasing execution frequency. However, the amplitude of the differences between execution frequencies varied as a function of age and coordination mode.

The high test-retest stability coefficients confirm that the present field test represents a reliable tool to quantify older individual's performance on cyclic coupled movements of hand and foot allowing large-scale evaluations with an inexpensive apparatus. Aging generally harms homolateral inter-limb coordination performance, but a more complex pattern of effects emerges when coordination mode, and frequency of execution are manipulated. In fact, age-related performance impairments were most pronounced during anti-phase movements, that need increased monitoring and attentional allocation in order to inhibit the natural in-phase mode, and at high execution frequencies, that are strongly affected by age-related muscle weakness, prolonged reaction times, and changes in stretch reflexes.