The purpose of this study was to examine the reliability of a new upper body medicine ball push-press (MBP-P) test. Twenty-three strength trained volunteers performed a series of supine MBP-P throws using loads representing 5% and10% of their 5RM bench press (5 repetitions at each load). Throws were performed on a force platform (2000 Hz), with medicine ball kinematic data collected using a high-speed motion capture (500 Hz). Testing was repeated after 7–10 days to quantify intertest reliability. Maximal force (Fmax), impulse at Fmax, time to Fmax, and maximum rate of force development (RFDmax) were all calculated from the force platform outputs, with maximum ball velocity (Velmax) and maximum ball acceleration (Accelmax) developed from the kinematic data. Reliability was assessed using intraclass correlation (ICC), coefficient of variation (%CV), and typical error. Medicine ball kinematic variables were more reliable (CV% = 2.6–5.3, ICC = 0.87–0.95) than the various force platform derived power variables (CV% = 7.9–26.7, ICC = 0.51–0.90). The MBP-P test produces reliable data and can be used to quantify many standard power based measures, with the key findings have implications for athletic populations requiring high velocity, light load upper body pushing power.
Mark G.L. Sayers and Stephen Bishop
Mark G.L. Sayers, Amanda L. Tweddle and Jessika Morris
This project assessed dynamic balance and stability in aged lawn bowlers during the delivery stride. Participants were divided into two groups: aged 65 years or less (n = 14) and aged over 65 years (n = 16). Standard balance-based center of pressure (CoP) and ground reaction force variables were recorded and a Dynamic Postural Stability Index (DPSI) was used for calculating during ten deliveries. None of the balance variables correlated significantly with age although years of bowling experience correlated with DPSI scores (r = -.42, P = .019). The over 65 group had significantly greater variance in the mediolateral CoP movements, with no other significant differences in balance or postural stability variables between groups. Analysis of covariance indicated that the DPSI data were influenced significantly by bowling experience regardless of age group. It was concluded that in older aged lawn bowlers, playing experience rather than age is a key determinant of balance control during the lawn bowls delivery action.
Anna C. Severin, Brendan J. Burkett, Mark R. McKean, Aaron N. Wiegand and Mark G.L. Sayers
This study examined the effect of water immersion on trunk and lower limb kinematics during squat exercises in older participants. A total of 24 active older adults (71.4 ± 5.4 years) performed squats and split squats on land and while partially submerged in water. Inertial sensors (100 Hz) were used to record trunk and lower body kinematics. Water immersion increased the squat depth (squat: p = .028, d = 0.63 and split squat: p = .005, d = 0.83) and reduced the trunk flexion range (squat: p = .006, d = 0.76 and split squat: p < .001, d = 1.35) during both exercises. In addition, water immersion increased the hip range of motion during the split squat (p = .002, d = 0.94). Waveform analyses also indicated differences in the timing of the movements. These results showed that water-based exercise generates a different exercise outcome and appears to provide an alternative option for older adults, enabling exercisers to perform these tasks in a manner not possible on land.