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Mark Watsford and Aron Murphy

This research examined the effects of respiratory-muscle (RM) training on RM function and exercise performance in older women. Twenty-six women (60–69 yr of age) were assessed for spirometry, RM strength (maximal inspiratory and expiratory pressure), inspiratory-muscle endurance, and walking performance to a perceived exertion rating of “hard.” They were randomly allocated to a threshold RM training group (RMT) or a nonexercising control group (CON) for 8 wk. After training, the 22% (inspiratory) and 30% (expiratory) improvements in RM strength in the RMT group were significantly higher than in the CON group (p < .05). The RMT group also displayed several significant performance improvements, including improved within-group treadmill performance time (12%) and reductions in submaximal heart rate (5%), percentage of maximum voluntary ventilation (16%), and perceived exertion for breathing (8%). RM training appears to improve RM function in older women. Furthermore, these improvements appear to be related to improved submaximal exercise performance.

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Sven Rees, Aron Murphy and Mark Watsford

This study was designed to investigate the effects of vibration on muscle performance and mobility in a healthy, untrained, older population. Forty-three participants (23 men, 20 women, 66–85 y old) performed tests of sit-to-stand (STS), 5- and 10-m fast walk, timed up-and-go test, stair mobility, and strength. Participants were randomly assigned to a vibration group, an exercise-without-vibration group, or a control group. Training consisted of 3 sessions/wk for 2 mo. After training, the vibration and exercise groups showed improved STS (12.4%, 10.2%), 5-m fast walk (3.0%, 3.7%), and knee-extension strength (8.1%, 7.2%) compared with the control (p < 0.05). Even though vibration training improved lower limb strength, it did not appear to have a facilitatory effect on functional-performance tasks compared with the exercise-without-vibration group. Comparable mobility and performance changes between the experimental groups suggest that improvements are linked with greater knee-extension strength and largely attributed to the unloaded squats performed by both exercise groups.

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Ken A. McLachlan, Aron J. Murphy, Mark L. Watsford and Sven Rees

Two popular methods of assessing lower body musculotendinous stiffness include the hopping and oscillation tests. The disparity and paucity of reliability data prompted this investigation into leg musculotendinous stiffness (Kleg) and ankle musculotendinous stiffness (Kank) measures. Kleg and Kank were assessed on three separate occasions in 20 female subjects. Kleg was determined using bilateral hopping procedures conducted at 2.2 Hz and 3.2 Hz frequencies. Kank was assessed by perturbation of the subject's ankle musculotendinous unit on an instrumented calf raise apparatus at 70% of maximum isometric force (MIF). Excellent reliability was produced for all Kleg measures between all days, whereas Kank exhibited acceptable reliability after one session of familiarization. No relationship was evident between Kleg and Kank. It was concluded that no familiarization session was required for Kleg at the test frequencies and conditions tested, whereas at least one familiarization session was needed to ensure the reliable assessment of Kank.

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Stephen J. Kelly, Aron J. Murphy, Mark L. Watsford, Damien Austin and Michael Rennie

Purpose:

To investigate the validity and reliability of accelerometry of the SPI-ProX II dual data logger (GPSports, Canberra, Australia).

Methods:

Controlled laboratory assessments determined the accuracy and reproducibility of raw accelerometer data. Intra- and interdevice reliability assessed the ability of the SPI-ProX II accelerometers to repeatedly measure peak gravitational accelerations (g) during impact-based testing. Static and dynamic validity testing assessed the accuracy of SPI-ProX II accelerometers against a criterion-referenced accelerometer. Dynamic validity was assessed over a range of frequencies from 5 to 15 Hz.

Results:

Intradevice reliability found no differences (P < .05) between 4 SPI-ProX II accelerometers, with a low coefficient of variation (1.87–2.21%). SPI-ProX II accelerometers demonstrated small to medium effect-size (ES) differences (0.10–0.44) between groups and excellent interdevice reliability, with no difference found between units (F = 0.826, P = .484). Validity testing revealed significant differences between devices (P = .001), with high percentage differences (27.5–30.5%) and a large ES (>3.44).

Conclusions:

SPI-ProX II accelerometers demonstrated excellent intra- and interaccelerometer reliability. However, static and dynamic validity were poor, and caution is recommended when measuring the absolute magnitude of acceleration, particularly for high-frequency movements. Regular assessment of individual devices is advised, particularly for mechanical damage and signal-drift errors. It is recommended that guidelines be provided by the manufacturer on measuring shifts in the base accelerometer signal, including time frames for assessing accelerometer axis, magnitude of errors, and calibration of accelerometers from a stable reference point.

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Mark L. Watsford, Aron J. Murphy, Matthew J. Pine and Aaron J. Coutts

Older adults’ participation in habitual exercise might be affected by alterations to respiratory mechanics such as decreased respiratory-muscle strength. This reduction can cause a decrease in efficiency of the ventilatory pump, potentially compromising exercise participation. This research examined the role of habitual exercise in respiratory-muscle function and the associated implications for exercise performance. Seventy-two healthy older adults (36 men, 64.9 ± 8.6 years, 177.2 ± 8.4 cm, 82.5 ± 11.9 kg; 36 women, 64.9 ± 9.5 years, 161.7 ± 6.4 cm, 61.6 ± 9.2 kg) undertook respiratory-function and walking-performance tests. Active men and women achieved higher scores than their inactive counterparts for all tests except spirometry, where no differences were evident. The results indicate that a significant amount of the elevated fitness level might be accounted for by increased endurance capacity of the inspiratory muscles. Inactive older individuals might be at risk for inadequate respiratory-muscle strength, so interventions should be considered.