Abstract
OBJECTIVE: The purpose of this study was to determine the safety and feasibility of subacute upper limb resistance exercise on sternal micromotion and pain and the reliability of sternal ultrasound assessment following cardiac surgery via median sternotomy. METHODS: This experimental study used a pretest-posttest design to investigate the effects of upper limb resistance exercise on the sternum in patients following their first cardiac surgery via median sternotomy. Six bilateral upper limb machine-based exercises were commenced at a base resistance of 20 lb (9 kg) and progressed for each participant. Sternal micromotion was assessed using ultrasound at the mid and lower sternum at 2, 8, and 14 weeks postsurgery. Intrarater and interrater reliability was calculated using intraclass correlation coefficients (ICCs). Participant-reported pain was recorded at rest and with each exercise using a visual analogue scale. RESULTS: Sixteen adults (n = 15 males; 71.3 [SD = 6.2] years of age) consented to participate. Twelve participants completed the study, 2 withdrew prior to the 8-week assessment, and 2 assessments were not completed at 14 weeks due to assessor unavailability. The highest median micromotion at the sternal edges was observed during the bicep curl (median = 1.33 mm; range = -0.8 to 2.0 mm) in the lateral direction and the shoulder pulldown (median = 0.65 mm; range = -0.8 to 1.6 mm) in the anterior-posterior direction. Furthermore, participants reported no increase in pain when performing any of the 6 upper limb exercises. Interrater reliability was moderate to good for both lateral-posterior (ICC = 0.73; 95% CI = 0.58 to 0.83) and anterior-posterior micromotion (ICC = 0.83; 95% CI = 0.73 to 0.89) of the sternal edges. CONCLUSION: Bilateral upper limb resistance exercises performed on cam-based machines do not result in sternal micromotion exceeding 2.0 mm or an increase in participant-reported pain. IMPACT: Upper limb resistance training commenced as early as 2 weeks following cardiac surgery via median sternotomy and performed within the safe limits of pain and sternal micromotion appears to be safe and may accelerate postoperative recovery rather than muscular deconditioning.