The relationship between balance control and thigh muscle strength and muscle activity in persons with incomplete spinal cord injury.

STUDY DESIGN: Cross-sectional study. OBJECTIVES: A spinal cord injury (SCI) can compromise the ability to maintain sufficient balance control during activities in an upraised position. The objective of the study was to explore the relationship between balance control and muscle strength and muscle activation in the lower extremities in persons with incomplete SCI (iSCI). SETTING: Sunnaas Rehabilitation Hospital, Norway. METHODS: Thirteen men and two women with iSCI and 15 healthy, matched controls were included. Performance of the Berg Balance Scale (BBS) short version (7 items) was used to indicate balance control. Maximal voluntary contraction (MVC) was performed to measure isometric muscle strength in thigh muscles (knee extension/flexion), while surface electromyography (EMG) was measured from M. Vastus Lateralis and M. Biceps Femoris. The relative activation of each muscle during each of the BBS tasks was reported as the percentage of the maximal activation during the MVC (%EMGmax). RESULTS: The iSCI participants had a significantly lower BBS sum score and up to 40% lower muscle strength in knee- flexion and extension compared to the matched healthy controls. They also exhibited a significantly higher %EMGmax, i.e. a higher muscle activation, during most of the balance tests. Univariate regression analysis revealed a significant association between balance control and mean values of %EMGmax in Biceps Femoris, averaged over the seven BBS tests. CONCLUSIONS: The participants with iSCI had poorer balance control, reduced thigh muscle strength and a higher relative muscle activation in their thigh muscles, during balance-demanding activities.

Exercise intensity during exergaming in wheelchair-dependent persons with SCI.

STUDY DESIGN: Cross-sectional study. OBJECTIVES: It is challenging for persons with SCI, especially those who are wheelchair dependent, to find suitable and motivating aerobic exercise modes. Exergaming might be a good option, since it is relatively cheap and can be played at home, alone or with others. However, it is unknown if exergaming is performed at a sufficient exercise intensity. SETTING: Sunnaas Rehabilitation Hospital, Norway. METHODS: Twenty-two men and two women (n = 24) with chronic SCI (AIS A-C), all wheelchair users, were included during inpatient rehabilitation. All participant performed a maximal graded arm-crank test (pretest), while measuring peak oxygen uptake (VO2peak) and peak heart rate (HRpeak). The day after they had a practice playing session with three different exergames (X-box Kinect, Fruit Ninja; Nintendo Wii, Wii Sports Boxing; VR Oculus Rift, boxing). The following day, participants played each exergame for 15 min. During these 45 min of exergaming, exercise intensity, based on VO2peak and HRpeak from the pretest, was monitored. RESULTS: Approximately 30 of the 45 min of exergaming was performed at moderate or high intensity. Participants exercised on average 24.5 min (95%CI 18.7-30.5) at moderate intensity (>50-80% VO2peak) and 6.6 min (95%CI 2.2-10.8) at high intensity (>80% VO2peak). CONCLUSIONS: The participants were able to exercise at moderate or high intensity during exergaming in a considerable amount of time. Exergaming seems to be suitable for aerobic exercise at an intensity that can provide health benefits in wheelchair-dependent persons with SCI.

Balance Training in Older Adults Using Exergames: Game Speed and Cognitive Elements Affect How Seniors Play.

Falls in older adults are a serious threat to their health and independence, and a prominent reason for institutionalization. Incorrect weight shifts and poor executive functioning have been identified as important causes for falling. Exergames are increasingly used to train both balance and executive functions in older adults, but it is unknown how game characteristics affect the movements of older adults during exergaming. The aim of this study was to investigate how two key game elements, game speed, and the presence of obstacles, influence movement characteristics in older adults playing a balance training exergame. Fifteen older adults (74 ± 4.4 years) played a step-based balance training exergame, designed specifically for seniors to elicit weight shifts and arm stretches. The task consisted of moving sideways to catch falling grapes and avoid obstacles (falling branches), and of raising the arms to catch stationary chickens that appeared above the avatar. No steps in anterior-posterior direction were required in the game. Participants played the game for eight 2 min trials in total, at two speed settings and with or without obstacles, in a counterbalanced order across participants. A 3D motion capture system was used to capture position data of 22 markers fixed to upper and lower body. Calculated variables included step size, step frequency, single leg support, arm lift frequency, and horizontal trunk displacement. Increased game speed resulted in a decrease in mean single support time, step size, and arm lift frequency, and an increase in cadence, game score, and number of error messages. The presence of obstacles resulted in a decrease in single support ratio, step size, cadence, frequency of arm lifts, and game score. In addition, step size increased from the first to the second trial repetition. These results show that both game speed and the presence of obstacles influence players' movement characteristics, but only some of these effects are considered beneficial for balance training whereas others are detrimental. These findings underscore that an informed approach is necessary when designing exergames so that game settings contribute to rather than hinder eliciting the required movements for effective balance training.