Effects of different increments in workload and duration on peak physiological responses during seated upper-body poling

Hybrid high-intensity interval training using functional electrical stimulation leg cycling and arm ski ergometer for people with spinal cord injuries: a feasibility study

Aim

The aim was to assess safety and feasibility of Hybrid High-Intensity Interval Training (HIIT) using Functional Electrical Stimulation (FES) leg cycling and arm ski ergometer in people with Spinal Cord Injuries (SCI).

Method

Eight outpatients (mean age 42.8 years; 7 men) with stable SCI paraplegia (mean 14.5 years since injury) participated in hybrid HIIT (90% peak watts; 4 × 4–min intervals), three times a week (over 8 weeks). Primary outcomes were Adverse Events (AE), participant acceptability, shoulder pain, training intensity (% peak watts), and attendance.

Secondary outcomes were effect on peak oxygen uptake (VO₂peak) during FES hybrid poling, mean watts, self-reported leisure time physical activity, quality of life, and fatigue.

Results

No serious AE occurred; acceptability with the training modality was high, while shoulder pain increased by 9% (SD 95.2). During training, 50% of the participants reached > 90% peak watts during the intervals, three with the legs (FES cycle) and one with the arms (Ski-Erg). Overall, mean training intensity (% peak watts) was 92% (SD 18.9) for legs and 82% (SD 10.3) for arms. Proportion of fulfilled training minutes was 82% (range 36–100%); one participant dropped out after 6 weeks due to back pain. Mean VO₂peak increased by 17% (SD 17.5). Participants reported increased leisure time physical activity and health-related quality of life, besides reduced fatigue.

Conclusion

Hybrid HIIT was safe for people with SCI paraplegia. The majority of the criteria for feasibility were met with acceptable attendance rate, limited drop out, participants enjoyed training, and increased VO₂peak and mean watts. However, the intensity of 90% peak watts was reached by < 60% of the participants despite high RPE ratings during training. The method of measuring and calculating intensity needs to be studied further before a study using this HIIT protocol is undertaken.

Trial registration

Clinicaltrials.gov, NCT04211311, registered 12 December 2019 retrospectively registered

Supplementary Information

The online version contains supplementary material available at 10.1186/s40814-022-00997-2.

Test-Retest Reliability of Physiological Variables During Submaximal Seated Upper-Body Poling in Able-Bodied Participants

Purpose: To investigate the test–retest reliability of physiological variables across four different test days and four different submaximal exercise intensities during seated upper-body poling (UBP).

Methods: Thirteen abled-bodied, upper-body trained men (age 29±3years; body mass 84±12kg; height 183±5cm) performed four submaximal 4-min stages of seated UBP on four separate test days. The four submaximal stages were set at individual power outputs corresponding to a rating of perceived exertion of 9, 11, 13, and 15. The absolute reliability for pairwise test-day comparisons of the physiological variables was investigated with the smallest detectable change percentage (%SDC) and the relative reliability with the interclass correlation coefficient (ICC).

Results: Absolute and relative reliability across test-day comparisons and submaximal stages were moderate to excellent for all variables investigated (V̇O₂ – %SDC range: 5–13%, ICC range: 0.93–0.99; HR – %SDC range: 6–9%, ICC range: 0.91–0.97) other than blood lactate, for which absolute reliability was poor and relative reliability highly variable (%SDC range: 26–69%, ICC range: 0.44–0.92). Furthermore, absolute and relative reliability were consistent across the low-to-moderate exercise intensity spectrum and across test days.

Conclusion: Absolute and relative test–retest reliability were acceptable for all investigated physiological variables but blood lactate. The consistent test–retest reliability across the exercise intensity spectrum and across test days indicates that a familiarization period to the specific exercise modality may not be necessary. For generalizability, these findings need to be confirmed in athletes with a disability by future large-scale studies.

Comparison of Physiological and Biomechanical Responses to Flat and Uphill Cross-Country Sit-Skiing in Able-Bodied Athletes

PURPOSE

To compare peak work rate (WRpeak) and associated physiological and biomechanical performance-determining variables between flat and uphill cross-country (XC) sit-skiing.

METHODS

Fifteen able-bodied male XC skiers completed 2 test sessions, each comprising four 4-minute submaximal stages, followed by an incremental test to exhaustion and a verification test in a sit-ski on a roller-ski treadmill. The test sessions were counterbalanced by the incline, being either 0.5% (FLAT) or 5% (UPHILL). The authors compared WRpeak and peak oxygen uptake, as well as physiological variables, rating of perceived exertion, gross efficiency, and cycle characteristics at identical submaximal work rate, between FLAT and UPHILL.

RESULTS

In UPHILL, WRpeak was 35% higher compared to FLAT (P < .001), despite no difference in peak oxygen uptake (P = .9). The higher WRpeak in UPHILL was achieved through more work per cycle, which was enabled by the twice as long poling time, compared to FLAT (P < .001). Submaximal gross efficiency was 0.5 to 2 percentage points lower in FLAT compared to UPHILL (P < .001), with an increasing difference as work rate increased (P < .001). Neither cycle rate nor work per cycle differed between inclines when compared at identical submaximal work rate (P > .16).

CONCLUSIONS

The longer poling times utilized in uphill XC sit-skiing enable more work per cycle and better gross efficiency, thereby allowing skiers to achieve a higher WRpeak compared to flat XC sit-skiing. However, the similar values of peak oxygen uptake between inclines indicate that XC sit-skiers can tax their cardiorespiratory capacity similarly in both conditions.