Exercise intensity during exergaming in wheelchair-dependent persons with SCI

Persons with spinal cord injury (SCI), particularly those who are wheelchair-dependent, face elevated risks of inactivity and related cardiometabolic complications, with reduced daily energy expenditure and low cardiorespiratory fitness (CRF). Evidence-based SCI exercise guidelines recommend at least 20 minutes of moderate-to-high intensity aerobic exercise twice weekly for health benefits. However, barriers such as accessibility and limited motivating options make adherence challenging. Exergaming—digital games requiring bodily movement—may be an accessible, engaging, and low-cost modality that can be performed at home. Prior work has often reported absolute intensities (VO2 or METs), which may not reflect relative effort in persons with physical disabilities. Relative intensity (percent of VO2peak or HRpeak) is more appropriate in this population. Only a few small studies have examined exergaming intensity relative to VO2peak/HRpeak in neurological populations, generally showing moderate intensities, but without fully accounting for influences of injury characteristics, fitness level, and game type. The present study aims to quantify relative exercise intensity (%VO2peak and %HRpeak) during exergaming in wheelchair-dependent persons with SCI after a maximal test, and secondarily to assess whether game type, CRF, and injury level affect the ability to achieve moderate and high intensities.

Previous studies have typically characterized exergaming intensity using absolute measures (VO2 or METs), often indicating low-to-moderate intensity, which may underestimate relative effort in individuals with disabilities. Relative intensity thresholds commonly used are: low (<50% VO2peak or <70% HRpeak), moderate (50–80% VO2peak or 70–85% HRpeak), and high (>80% VO2peak or >85% HRpeak). Two small studies in persons with neurological disabilities suggested exergaming can reach moderate intensity relative to VO2peak/HR measures. Widman et al. reported most participants with SCI achieved >50% VO2peak with GameCycle; Burns et al. found all achieved moderate intensity with GameCycle but fewer did so with XaviX Tennis, indicating game selection may influence intensity. Motivation and game characteristics may thus be important determinants, but prior work has not systematically examined effects of CRF level or injury level on achievable intensity during exergaming.

Design: Cross-sectional study at Sunnaas Rehabilitation Hospital, Norway. Participants: Of 31 recruited in 2018–2020, 24 wheelchair-dependent adults with chronic SCI (AIS A–C; injury level C5 or lower; ≥1 year post-injury; age ≥18) were included; exclusions were comorbidities limiting CRF. Wheelchair-dependent was defined as inability to stand upright without support. Procedures: After consent and medical clearance, participants completed a maximal graded arm-crank test (LODE ergometer) seated in their wheelchair. Warm-up: 5 minutes at 20 W, 60 rpm. Test: start 20 W for 3 minutes, then individualized 10–40 W increments every 3 minutes to volitional exhaustion. Hands were secured if needed. VO2 and HR were continuously measured; VO2peak defined as highest 30-second average VO2; HRpeak as highest measured HR. Two minutes post-test, fingertip blood lactate was sampled. A familiarization session (~45 minutes) with the three exergames occurred the following day. The exergame session (2–3 days later) included 5 minutes resting baseline, then three 15-minute game bouts with 5-minute rests: Fruit Ninja (Xbox Kinect), Wii Sports Boxing (Nintendo Wii), and Thrill of the Fight (VR Oculus Rift). Order was randomized via block randomization by drawing lots. Safety accommodations included chest Velcro for reduced trunk balance, taping controllers for grip, and strapping the wheelchair to a low platform. Participants were instructed to view exergaming as exercise; no motivational encouragement was provided. Measurements and equipment: VO2 via breath-by-breath open-circuit spirometry (Vmax 220), HR via Polar M400, respiratory exchange ratio (RER), and blood lactate (BIOSEN C-line). Maximality criteria for VO2peak were met if ≥3 of: VO2 plateau (<2 ml/kg/min increase with load), blood lactate ≥8 mmol/L, RER ≥1.15, or ≥90% of age-predicted maximal treadmill HR adjusted for arm cranking: HRmax(pred) = (211 − 0.64 × age) × 0.9. Data handling and analysis: Exercise intensity during exergaming was expressed relative to each participant’s VO2peak and HRpeak. Primary analyses were based on %VO2peak as a more valid indicator than HR. Intensity zones: low (<50% VO2peak or <70% HRpeak), moderate (50–80% VO2peak or 70–85% HRpeak), high (>80% VO2peak or >85% HRpeak). Statistical analyses (IBM SPSS v28): repeated-measures ANOVA compared intensities among games, with Fisher’s LSD post-hoc tests; linear regression examined association of CRF (VO2peak) with time >50% and >80% VO2peak; Mann–Whitney U compared cervical vs thoracic/lumbar groups. Alpha = 0.05.

• Sample: 24 participants (22 men, 2 women), ages 24–71; injury levels C5–C8 (n=6), T1–T6 (n=10), T7–T12 (n=8); AIS A (n=19), AIS B (n=3), AIS C (n=2). Twenty-one met ≥3 maximality criteria; three (C5/C6) met 1–2 criteria. Mean VO2peak 20.1 ± 5.0 ml/kg/min; HRpeak 161 ± 25 bpm.
• Overall exergaming intensity (45 minutes total): • By VO2peak: High (>80% VO2peak) 6.6 min (95% CI 2.2–10.8); Moderate (50–80% VO2peak) 24.5 min (95% CI 18.7–30.5); Low (<50% VO2peak) 13.9 min (95% CI 9.0–18.8). Total moderate-to-high: ~31 of 45 minutes. • By HRpeak: High (>85% HRpeak) 14 min (95% CI 7.4–21.2); Moderate (70–85% HRpeak) 14 min (95% CI 7.55–21.5); Low (<70% HRpeak) 17 min (95% CI 10.3–22.2). Total moderate-to-high: ~28 of 45 minutes.
• Between games: Time at moderate intensity did not differ significantly among Kinect Fruit Ninja, Wii Boxing, and VR Boxing. High-intensity time was 2.7 minutes greater in VR Boxing vs Kinect Fruit Ninja (p=0.03; 95% CI 0.2–5.2); no other significant differences.
• CRF level: Participants with VO2peak ≥20 ml/kg/min (n=9) vs <20 ml/kg/min (n=15) showed no significant differences in time >50% VO2peak (p=0.09) or >80% VO2peak (p=0.82). Mean time >50% VO2peak: lower CRF 32.6 ± 9.2 min vs higher CRF 25.9 ± 16.1 min.
• Injury level: Cervical vs thoracic/lumbar groups did not differ significantly in time >50% VO2peak (p=0.08) or >80% VO2peak (p=0.07). Means: cervical 37.8 min (95% CI 31.6–44.0) >50% VO2peak and 10.6 min (95% CI 0.9–20.5) >80% VO2peak; lower injury levels 27.0 min (95% CI 20.5–33.5) and 5.6 min (95% CI 1.7–9.5), respectively.
• Tolerability/safety: 23/24 completed 45 minutes; one stopped at 40 minutes due to shoulder pain; no other adverse events.

The study addressed whether exergaming can elicit sufficient relative aerobic intensity in wheelchair-dependent persons with SCI. Most participants achieved moderate-to-high intensity for a substantial portion (~31 minutes of 45) when intensity was assessed relative to VO2peak, suggesting exergaming can meet SCI aerobic activity recommendations when performed about 45 minutes twice weekly. Achieved intensity did not depend strongly on game type, CRF level, or injury level, though VR boxing yielded slightly more high-intensity time than Kinect Fruit Ninja. These findings align with prior small studies showing that certain exergames can reach moderate intensity in SCI, while also highlighting that intensity varies by game and individual factors. Practical implications include the feasibility of home-based exergaming as a motivating, accessible modality for improving CRF and potentially reducing cardiometabolic risk in wheelchair-dependent individuals. However, HR-based intensity classification appeared to overestimate high-intensity time compared with VO2-based measures, underscoring the importance of VO2-referenced assessments when feasible.

Exergaming enabled wheelchair-dependent persons with SCI to exercise at moderate or high intensity for a considerable portion of a 45-minute session, indicating that it is a suitable, accessible, and potentially motivating aerobic exercise modality for achieving health-beneficial intensity. Differences across the tested games were minimal for moderate intensity, with VR boxing showing slightly more high-intensity time than Kinect. Neither CRF level nor injury level significantly affected the ability to achieve moderate-to-high intensity. Future research should employ longitudinal, home-based interventions to evaluate feasibility, adherence, safety, and effects on metabolic health and fitness, and examine how game selection and individual motivational factors influence training intensity and outcomes.

• Cross-sectional, single-session design limits causal inference and does not assess long-term adherence, feasibility, or training effects.
• Only three exergames/consoles were tested; broader game selections may yield different intensities.
• Individual motivation, gaming interest/experience, and other person-dependent factors that likely influence intensity were not assessed; authors note this as a weakness.
• HR-based intensity appeared to overestimate time at high intensity relative to VO2-based measures.
• Seven participants had missing lactate data due to technical failure, potentially affecting maximality verification.
• One participant experienced shoulder pain; untrained users may require progressive introduction and supervision to avoid overuse.