Different motor tasks impact differently on cognitive performance of older persons during dual task tests.

BACKGROUND: Dual task paradigm states that the introduction of a second task during a cognitive or motor performance results in a decreased performance in either task. Treadmill walk, often used in clinical applications of dual task testing, has never been compared to overground walk, to ascertain its susceptibility to interference from a second task. We compared the effects of overground and treadmill gait on dual task performance. METHODS: Gait kinematic parameters and cognitive performance were obtained in 29 healthy older adults (mean age 75 years, 14 females) when they were walking freely on a sensorized carpet or during treadmill walking with an optoelectronic system, in single task or dual task conditions, using alternate repetition of letters as a cognitive verbal task. FINDINGS: During overground walking, speed, cadence, step length stride length, and double support time (all with P value<0.001) and cognitive performance (number of correct words, P<0.001) decreased substantially from single to dual task testing. When subjects walked at a fixed speed on the treadmill, cadence decreased significantly (P=0.005), whereas cognitive performance remained unaffected. INTERPRETATION: Both motor and cognitive performances decline during dual task testing with overground walking. Conversely, cognitive performance remains unaffected in dual task testing on the treadmill. In the light of current dual task paradigm, these findings may have relevant implication for our understanding of motor control, as they suggest that treadmill walk does not involve brain areas susceptible to interference from the introduction of a cognitive task.

Effects of a structured physical activity intervention on measures of physical performance in frail elderly patients after cardiac rehabilitation: a pilot study with 1-year follow-up.

The objective of this prospective randomized controlled study was to compare the long-term effects of a structured physical activity intervention with those of aerobic exercises alone, in a cohort of elderly patients who had undergone elective cardiac surgery, and who were classified as frail at the end of rehabilitation based on their Short Physical Performance Battery (SPPB) score. At the end of rehabilitation, 140 frail elderly patients were randomly allocated either to the intervention group (IG) or to the control group (CG). CG participants received the usual aerobic exercise prescription, while IG participants were also taught additional exercises for strength, flexibility, balance and coordination. The improvement in SPPB score after 1 year was the outcome of the study. IG showed a significant improvement in SPPB score (9.0 ± 1.1 vs. 7.7 ± 1.4, p < 0.001), while no significant change was found in CG (7.7 ± 1.6 vs. 7.6 ± 1.5, p = 0.252). IG also showed a significantly higher proportion of participants who improved their SPPB score of at least 1 point (70 vs. 37%, p < 0.001). In conclusions, our structured physical activity intervention significantly improves the SPPB score in frail elderly patients who have undergone elective cardiac surgery. An intervention that improves the SPPB score might delay the occurrence of mobility disability.

The improvement of walking speed after cardiac rehabilitation is associated with the reduction in the metabolic cost of walking in older persons.

BACKGROUND: To walk a given distance older persons consume more metabolic energy than younger adults across all speeds. As physical activity interventions improve a variety of physical performance measures in older persons, including walking speed, in this study we hypothesized that the improvement of walking speed might be associated with the reduction of the metabolic cost of walking and we tested our hypothesis in a selected sample of older patients receiving cardiac rehabilitation. METHODS: In 120 patients (88 men and 32 women, mean age 74.1 years±SD 5.0) we assessed energy expenditure during the 6-min Walk Test (6mWT) before and after the rehabilitation using a portable system for direct calorimetry. RESULTS: On the 6mWT performed after the rehabilitation patients significantly increased total energy expenditure (28.0 kcal±SD 8.3 vs. 25.7 kcal±SD 7.6, p<0.001), the distance walked (398 m±SD 93 vs. 343 m±SD 95, p<0.001) and, consequently, walking speed (1.11 m/s±SD 0.26 vs. 0.95m/s±SD 0.26, p<0.001) while the metabolic cost of walking, i.e. the amount of energy used to move a body mass of 1 kg for a distance of 1m, was significantly reduced (1.00 cal/kg/m±SD 0.19 vs. 1.11 cal/kg/m±SD 0.32, p<0.001). CONCLUSIONS: In older patients receiving cardiac rehabilitation the improvement of walking speed is associated with the improvement of walking economy. This might be a contributory factor to the favourable effects of physical activity interventions on physical performance measures.