A ground-based comparison of the Muscle Atrophy Research and Exercise System (MARES) and a commercially available isokinetic dynamometer

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• 作者：Kirk L. English ; Kyle J. Hackney ; John K. De Witt ; Robert J. Ploutz-Snyder ; Elizabeth L. Goetchius ; Lori L. Ploutz-Snyder
• 关键词：Strength test ; ISS ; Spaceflight ; Microgravity ; Peak torque ; In-flight
• 刊名：Acta Astronautica
• 出版年：2013
• 出版时间：November, 2013
• 年：2013
• 卷：92
• 期：1
• 页码：3-9
• 全文大小：967 K

文摘

Introduction

International Space Station (ISS) crewmembers perform muscle strength and endurance testing pre- and postflight to assess the physiologic adaptations associated with long-duration exposure to microgravity. However, a reliable and standardized method to document strength changes in-flight has not been established. To address this issue, a proprietary dynamometer, the Muscle Atrophy Research and Exercise System (MARES) has been developed and flown aboard the ISS. The aims of this ground-based investigation were to: (1) evaluate the test-retest reliability of MARES and (2) determine its agreement with a commercially available isokinetic dynamometer previously used for pre- and postflight medical testing.

Methods

Six males (179.5¡À4.7 cm; 82.0¡À8.7 kg; 31.3¡À4.0 yr) and four females (163.2¡À7.3 cm; 63.2¡À1.9 kg; 32.3¡À6.8 yr) completed two testing sessions on a HUMAC NORM isokinetic dynamometer (NORM) and two sessions on MARES using a randomized, counterbalanced, cross-over design. Peak torque values at 60¡ã and 180¡ã s^?1 were calculated from five maximal repetitions of knee extension (KE) and knee flexion (KF) for each session. Total work at 180¡ã s^?1 was determined from the area under the torque versus displacement curve during 20 maximal repetitions of KE and KF.

Results

Intraclass correlation coefficients were relatively high for both devices (0.90-0.99). Only one dependent measure, KE peak torque at 60¡ã s^?1 exhibited good concordance between devices (¦Ñ=0.92) and a small average difference (0.9¡À17.3 N m).

Conclusion

MARES demonstrated acceptable test-retest reliability and thus should serve as a good tool to monitor in-flight strength changes. However, due to poor agreement with NORM, it is not advisable to compare absolute values obtained on these devices.