Electrical Assisted Cycling: Energy Expenditure, Heart Rate and Power Output

Abstract

PURPOSE: To assess the potential of an electric bicycle as a novel device for meeting the physical activity guidelines, in terms of energy expenditure (EE). Does the self selected physiological load of electric assisted cycling meet the recommended intensity standards for health enhancing physical activity (4 MET for moderate intensity and 55% of the maximum heart rate for vigorous intensity)? METHODS: 12 habitually active subjects (age 32-60 years; 6M, 6F) were requested to cycle a track of 4.3 km at an intensity they would normally choose for cycling to work, under three different conditions: no support, eco support and power support. EE (K4b2 Cosmed, Italy) was estimated and heart rate (Polar S810i Electro, Finland) was measured. The bicycle was equipped with the SRM Training System (Schoberer Rad Messtechnik, Germany) to measure power output, pedalling rate and cycle velocity. RESULTS: For unsupported cycling (UN) EE was 6.1 ± 1.6 Metabolic Equivalent (MET), for cycling with Eco support (ECO) EE was 5.7 ± 1.2 and for cycling with Power support (POWER) EE was 5.2 ± 1.4. EE was significantly lower with POWER compared to UN. No differences were found between UN and ECO and ECO and POWER. Mean heart rate was 124 ± 23 (74 ± 14% of the estimated maximum heart rate (HRmax)), 116 ± 22 (69 ± 13% HRmax) and 112 ± 23 beats per minute (67% ± 14% HRmax) for UN, ECO and POWER respectively. Mean heart rate was significantly higher for UN compared to ECO and POWER. No differences were found between ECO and POWER. Mean power output was 118 ± 31, 102 ± 25 and 94 ± 29 Watt for UN, ECO and POWER respectively and was significantly different between all three conditions. Mean pedaling rate was 55 ± 6, 52 ± 6 and 49 ± 7 (rpm) for UN, ECO and POWER respectively. Mean pedaling rate was significantly higher for UN compared to ECO and POWER. No differences were found between the two conditions with support. Mean cycling speed was 19.6 ± 2.4, 21.1 ± 2.2 and 23.4 ± 1.7 km/h for UN, ECO and POWER respectively and differed significantly between the three conditions. CONCLUSIONS: EE during electrical assisted cycling, in all three measured conditions, is sufficiently high to meet both moderate and vigorous intensity standards of the physical activity guidelines for adults. A higher speed was achieved while cycling with support, but less power was produced compared to unsupported cycling.