Tom Tørhaug

Maximal Strength Training Enhances Strength and Functional Performance in Chronic Stroke Survivors

ObjectiveThis study aimed to demonstrate that maximal strength training improves muscle strength and to assess the effect of training on function, aerobic status, and quality-of-life among chronic stroke survivors. DesignTen patients acted as their own controls for 4 wks, before an 8-week training intervention. Patients trained 3 days/wk, with four sets of four repetitions at 85%–95% one repetition maximum in unilateral leg press and plantarflexion with an emphasis on maximal mobilization of force in the concentric phase. ResultsAfter training, leg press strength improved by 30.6 kg (75%) and 17.8 kg (86%); plantarflexion strength improved by 35.5 kg (89%) and 28.5 kg (223%) for the unaffected and affected limbs, respectively, significantly different from the control period (all P < 0.01). The 6-min walk test improved by 13.9 m (within training period; P = 0.01), and the Timed Up and Go test time improved by 0.6 secs (within training period; P < 0.05). There were no significant changes in walking economy, peak aerobic capacity, Four-Square Step Test, or health-related quality-of-life after training. ConclusionsMaximal strength training improved muscle strength in the most affected as well as in the nonaffected leg and improved Timed-Up-And-Go time and 6-min walk distance but did not alter Four-Step Square Test time, aerobic status, or quality-of-life among chronic stroke survivors.

Effect of High Aerobic Intensity Interval Treadmill Walking in People With Chronic Stroke: A Pilot Study With One Year Follow-Up

Abstract Objective: To determine the physiological and functional responses from high aerobic intensity treadmill walking in 4 x 4-minute intervals in people with chronic stroke and to evaluate the feasibility of this mode of training. Method: This was a baseline control trial with 1 year follow-up in an outpatient rehabilitation setting at a university hospital. Eight people with chronic stroke participated in and completed the study. Their mean age was 48.9 (± 10.6) years. We tested uphill treadmill walking in 4 x 4-minute work periods at an intensity between 85% and 95% of peak heart rate from initial maximal treadmill testing. There were 3-minute active breaks between the intervals. The main outcome measures were peak oxygen uptake (VO2peak) and walking economy (Cw). Overall compliance and adverse events determine the feasibility. Results: VO2peak increased from 2.32 (± 0.44) to 2.60 (± 0.55) L • min–1 post training (P = .003). Walking economy (Cw) improved from 1.12 (± 0.15) to 1.04 (± 0.18) L • min–1 (P = .043). At 1 year follow-up, VO2peak was 2.59 (±0.58) L • min –1 and was not significantly different from posttraining measurement (P = 1.00). Cw was 1.19 (± 0.15) L • min–1 at 1 year follow-up and thus was worse than post training (P = .023). Functional improvements were found in the 6-minute walk test (6MWT) (P = .020), 10-meter walk test (10MWT) (P = .032), and Timed Up and Go test (TUG) (P = .002) at post tests. Conclusions: High aerobic intensity interval treadmill walking significantly increased VO2peak and improved Cw in these subjects. The training was feasible and may have important implications for cardiovascular health and future rehabilitation programs in this population.

Effect of lower extremity functional electrical stimulation pulsed isometric contractions on arm cycling peak oxygen uptake in spinal cord injured individuals.

OBJECTIVE To compare peak oxygen uptake (VO2peak) between: (i) functional electrical stimulation lower extremity pulsed isometric muscle contractions combined with arm cycling (FES iso hybrid), (ii) functional electrical stimulation cycling combined with arm cycling (FES hybrid cycling), and (iii) arm cycling exercise (ACE) in individuals with spinal cord injury with level of injury above and below T6. DESIGN Cross-over repeated measures design. METHODS/PARTICIPANTS: Individuals with spinal cord injury (n = 15) with level of injury between C4 and T12, were divided into groups; above (spinal cord injury - high, n = 8) and below (spinal cord injury - low, n = 7) T6 level. On separate days, VO2peak was compared between: (i) ACE, (ii) FES iso hybrid, and (iii) FES hybrid cycling. RESULTS In the SCI-high group, FES iso hybrid increased VO2peak (17.6 (standard deviation (SD) 5.0) to 23.6 (SD 3.6) ml/kg/min; p = 0.001) and ventilation (50.4 (SD 20.8) to 58.2 (SD 20.7) l/min; p = 0.034) more than ACE. Furthermore, FES hybrid cycling resulted in a 6.8 ml/kg/min higher VO2peak (p = 0.001) and an 11.0 litres/minute (p = 0.001) higher ventilation. ACE peak workload was 10.5 W (p = 0.001) higher during FES hybrid cycling compared with ACE. In the spinal cord injury - low group, no significant differences were found between the modalities. CONCLUSION VO2peak increased when ACE was combined with FES iso hybrid or FES hybrid cycling in persons with spinal cord injury above the T6 level. Portable FES may serve as a less resource-demanding alternative to stationary FES cycling, and may have important implications for exercise prescription for spinal cord injury.

Impact of maximal strength training on work efficiency and muscle fiber type in the elderly: Implications for physical function and fall prevention

ABSTRACT Although aging is typically associated with a decreased efficiency of locomotion, somewhat surprisingly, there is also a reduction in the proportion of less efficient fast‐twitch Type II skeletal muscle fibers and subsequently a greater propensity for falls. Maximal strength training (MST), with an emphasis on velocity in the concentric phase, improves maximal strength, the rate of force development (RFD), and work efficiency, but the impact on muscle morphology in the elderly is unknown. Therefore we evaluated force production, walking work efficiency, and muscle morphology in 11 old (72 ± 3 years) subjects before and after MST of the legs. Additionally, for reference, the MST‐induced morphometric changes were compared with 7 old (74 ± 6 years) subjects who performed conventional strength training (CST), with focus on hypertrophy, as well as 13 young (24 ± 2 years) controls. As expected, MST in the old improved maximal strength (68%), RFD (48%), and work efficiency (12%), restoring each to a level similar to the young. However, of importance, these MST‐induced functional changes were accompanied by a significant increase in the size (66%) and shift toward a larger percentage (56%) of Type II skeletal muscle fibers, mirroring the adaptations in the hypertrophy trained old subjects, with muscle composition now being similar to the young. In conclusion, MST can increase both work efficiency and Type II skeletal muscle fiber size and percentage in the elderly, supporting the potential role of MST as a countermeasure to maintain both physical function and fall prevention in this population. HighlightsHigh intensity maximal strength training (MST) improves work efficiency.In the current study we provide new insight in the underlying muscle morphology.Despite associated with neural adaptations, MST leads to Type II fiber alterations.Similar to moderate intensity hypertrophy‐inducing strength trainingMST is an excellent strategy for improving physical function and preventing falls.

Arm Crank and Wheelchair Ergometry Produce Similar Peak Oxygen Uptake but Different Work Economy Values in Individuals with Spinal Cord Injury

Objective. To study whether values for peak oxygen uptake (VO2peak) and work economy (WE) at a standardized workload are different when tested by arm crank ergometry (ACE) and wheelchair ergometry (WCE). Methods. Twelve paraplegic men with spinal cord injury (SCI) in stable neurological condition participated in this cross-sectional repeated-measures study. We determined VO2peak and peak power output (POpeak) values during ACE and WCE in a work-matched protocol. Work economy was tested at a standardized workload of 30 Watts (W) for both ACE and WCE. Results. There were no significant differences in VO2peak (mL·kg−1·min−1) between ACE (27.3 ± 3.2) and WCE (27.4 ± 3.8) trials, and a Bland-Altman plot shows that findings are within 95% level of agreement. WE or oxygen consumption at 30 W (VO2-30W) was significantly lower during WCE compared to ACE (P < 0.039). Mean (95% CI) POpeak (W) were 130 (111–138) and 100 (83–110) during ACE and WCE, respectively. Conclusion. The findings in the present study support the use of both ACE and WCE for testing peak oxygen uptake. However, WE differed between the two test modalities, meaning that less total energy is used to perform external work of 30 W during wheelchair exercise when using this WCE (VP100 Handisport ergometer). Clinical Trials Protocol Record is NCT00987155/4.2007.2271.

The effect from maximal bench press strength training on work economy during wheelchair propulsion in men with spinal cord injury

Objective:To assess the effect from maximal bench press strength training (MST) on wheelchair propulsion work economy (WE).Study design:Pretest–posttest case–control group design.Setting:St Olavs Hospital, Trondheim, Norway.Methods:Seventeen male individuals with spinal cord injury (SCI) paraplegia were allocated to either MST bench press (n=11) or the control group (CG) (n=7). The MST group trained bench press three times per week, for 6 weeks, starting at 85–95% of their pretest bench press one-repetition maximum (1RM). For calculation of WE during wheelchair propulsion, oxygen uptake (VO2) measurements were collected during wheelchair ergometry (WCE) at submaximal workload of 50 W. Similarly, peak oxygen uptake (VO2peak) and peak power output (W) were measured during WCE.Results:Individuals in the MST regimen significantly improved WE compared with the CG by 17.3 % (mean between-group differences: 95% confidence interval) of 2.63 ml kg−1 min−1: (−4.34, −0.91) (P=0.007). Between pretest and posttest, the increase in bench press 1RM was by 17% higher in the MST group compared with the CG. At peak testing, the MST group generated significantly higher peak power compared with the CG. All other physiological variables were comparable within and between groups.Conclusions:A 6-week MST bench press regimen significantly improved WE during wheelchair propulsion at 50 W workload. These preliminary data support a possible beneficial role for MST to reduce the energy cost of wheelchair propulsion for SCI individuals.

Effect of leg vascular occlusion on arm cycling peak oxygen uptake in spinal cord-injured individuals.

Study design:Cross-sectional single-subject design.Objectives:To determine whether leg vascular occlusion (LEVO) augment arm cycling (ACE) peak oxygen uptake in spinal cord-injured individuals.Setting:University Hospital, Norway.Methods:Fifteen individuals with C4 to T12 spinal cord injury (SCI) were recruited and divided into two groups: injury above (SCI-high, n=8) or below (SCI-low, n=7) the T6 level. Peak oxygen uptake (VO2peak) was measured during (1) ACE combined with LEVO, (2) ACE alone and (3) ACE combined with functional electrical stimulation cycling (FES hybrid cycling).Results:In the SCI-high group, VO2peak and peak Watt during ACE with LEVO were higher than ACE alone: 20.0 (±5.0) versus 17.6 (±5.0) ml kg−1 min−1 (P=0.006), and 72.5(±32) versus 80.0 (±34) Watt (P=0.016), respectively. However, FES hybrid cycling VO2peak was significantly higher than ACE with LEVO: 24.4 (±4.1) versus 20.0 (±5.0) ml kg−1 min−1 (P=0.006). In the SCI-low group, there was no difference in VO2peak and related parameters between the three modalities.Conclusions:For spinal cord-injured individuals with injury level above T6 (high) in the present study, LEVO combined with ACE augment VO2peak. However, this acute increase in VO2peak was lower than when FES cycling was combined with ACE. These findings may have future implications for exercise prescription for spinal cord-injured individuals.

Arm Cycling Combined with Passive Leg Cycling Enhances VO2peak in Persons with Spinal Cord Injury Above the Sixth Thoracic Vertebra

Objective: To test whether passive leg cycling (PLC) during arm cycling ergometry (ACE) affects peak oxygen uptake (VO2peak) differently in individuals with spinal cord injury (SCI) at/above the 6th thoracic vertebra (T6) and below T6. Methods: We conducted a cross-sectional study, analyzed by univariate and multivariate regression models. Between- and within-group differences were examined during (a) ACE only, (b) ACE combined with PLC (ACE-PLC), and (c) ACE combined with functional electrical stimulation cycling (FES hybrid). Fifteen SCI subjects were recruited and grouped according to injury level: at/above T6 (SCI-high, n = 8) or below T6 (SCI-low, n = 7). VO2peak tests during ACE only, ACE-PLC, and FES hybrid were performed in random order on separate days. Results: In the SCI-high group, mean (SD) VO2peak was 19% higher during ACE-PLC than during ACE only [21.0 (3.8) vs 17.7 (5.0) mL·kg-1·min-1; p = .002], while VO2peak during FES hybrid cycling was 16% higher than during ACE-PLC [24.4 (4.1) mL·kg-1·min-1; p = .001]. No significant differences among exercise modalities were found for the SCI-low group. Conclusion: Additional training modalities (eg, PLC) during ACE facilitate exercise in SCI-high individuals, but not to the level of the FES hybrid method. Conversely, additional training modalities may not increase training load in SCI-low individuals.

Oxygen uptake during functional activities after stroke—Reliability and validity of a portable ergospirometry system

Background People with stroke have a low peak aerobic capacity and experience increased effort during performance of daily activities. The purpose of this study was to examine test-retest reliability of a portable ergospirometry system in people with stroke during performance of functional activities in a field-test. Secondary aims were to examine the proportion of oxygen consumed during the field-test in relation to the peak-test and to analyse the correlation between the oxygen uptake during the field-test and peak-test in order to support the validity of the field-test. Methods With simultaneous measurement of oxygen consumption, participants performed a standardized field-test consisting of five activities; walking over ground, stair walking, stepping over obstacles, walking slalom between cones and from a standing position lifting objects from one height to another. All activities were performed in self-selected speed. Prior to the field-test, a peak aerobic capacity test was performed. The field-test was repeated minimum 2 and maximum 14 days between the tests. ICC2,1 and Bland Altman tests (Limits of Agreement, LoA) were used to analyse test-retest reliability. Results In total 31 participants (39% women, mean (SD) age 54.5 (12.7) years and 21.1 (14.3) months’ post-stroke) were included. The ICC2,1 was ≥ 0.80 for absolute V̇O2, relative V̇O2, minute ventilation, CO2, respiratory exchange ratio, heart rate and Borgs rating of perceived exertion. ICC2,1 for total time to complete the field-test was 0.99. Mean difference in steady state V̇O2 during Test 1 and Test 2 was -0.40 (2.12) The LoAs were -3.75 and 4.51. Participants spent 60.7% of their V̇O2peak performing functional activities. Correlation between field-test and peak-test was 0.689, p = 0.001 for absolute and 0.733, p = 0.001 for relative V̇O2. Conclusions This study presents first evidence on reliability of oxygen uptake during performance of functional activities after stroke, showing very good test-retest reliability. The secondary analysis showed that the amount of energy spent during the field-test relative to the peak-test was high and the correlation between the two test was good, supporting the validity of this method.