Abstract
Objective: To determine whether stroke survivors could maintain workloads during functional task practice that can reach moderate levels of cardiometabolic stress (i.e., ≥40% oxygen uptake reserve (O2R) for ≥20 min) without the use of ergometer-based exercise.Design: Cross-sectional study using convenience sampling.Setting: Research laboratory in a tertiary rehabilitation hospital.Participants: Chronic hemiparetic stroke survivors (>6-months) who could provide consent and walk with or without assistance.Intervention: A single bout of intermittent functional training (IFT). The IFT protocol lasted 30 min and involved performing impairment specific multi-joint task-oriented movements structured into circuits lasting ~3 min and allowing 30–45 s recovery between circuits. The aim was to achieve an average heart rate (HR) 30-50 beats above resting without using traditional ergometer-based aerobic exercise.Outcome measures: Attainment of indicators for moderate intensity aerobic exercise. Oxygen uptake (O2), carbon dioxide production (CO2), and HR were recorded throughout the 30 min IFT protocol. Values were reported as percentage of O2R, HR reserve (HRR) and HRR calculated from predicted maximum HR (HRRpred), which were determined from a prior maximal graded exercise test.Results: Ten (3-female) chronic (38 ± 33 months) stroke survivors (70% ischemic) with significant residual impairments (NIHSS: 3 ± 2) and a high prevalence of comorbid conditions (80% ≥ 1) participated. IFT significantly increased all measures of exercise intensity compared to resting levels: O2 (Δ 820 ± 290 ml min−1, p < 0.001), HR (Δ 42 ± 14 bpm, p < 0.001), and energy expenditure (EE; Δ 4.0 ± 1.4 kcal min−1, p < 0.001). Also, mean values for percentage of O2R (62 ± 19), HRR (55 ± 14), and HRRpred (52 ± 18) were significantly higher than the minimum threshold (40%) indicating achievement of moderate intensity aerobic exercise (p = 0.004, 0.016, and 0.043, respectively).Conclusion: Sufficient workloads to achieve moderate levels of cardiometabolic stress can be maintained in chronic stroke survivors using impairment-focused functional movements that are not dependent on ergometers or other specialized equipment.
Highlights
Stroke mortality rate continues to decrease thanks to advances in medical management (Thrift et al, 2017) and emergency medical care (Crichton et al, 2016)
Maximal HR recorded during the graded exercise test (GXT) was 150 ± 26 bpm, which was within 2% of age-predicted values
The key finding of the current study was that chronic stroke survivors could sustain workloads during the intermittent functional training (IFT) protocol that were beyond the minimum intensity needed to increase cardiorespiratory fitness (American College of Sports Medicine, 2010) without the use of ergometers or other specialized equipment
Summary
Stroke mortality rate continues to decrease thanks to advances in medical management (Thrift et al, 2017) and emergency medical care (Crichton et al, 2016). Substantial resources are currently being employed to develop interventions that extend this time window and possibly even enhance repair mechanisms through use of stem cells, brain stimulation, and other pharmaceutical therapies (Ward, 2017). It is unclear whether the plateau of recovery observed post-stroke is due to a failure of the mechanisms underlying spontaneous biological recovery or if it is related to suboptimal dosage of physical and behavioral therapies (Ward, 2017). Stroke rehabilitation must be optimized to take advantage of intrinsic mechanisms for recovery and to enhance the effects of emerging therapies
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