Seven RCTs (224 participants) were included. Study size ranged from 24 to 46 participants. Five trials (168 participants) used conventional aerobic exercise as comparator and two trials (56 participants) used a control treatment.
The quality of most studies was poor: on the Jadad scale one scored 3, four scored 2 and two scored 1 (out of a maximum of five); on the PEDro score two studies scored 6, two scored 5, two scored 4 and one scored 2 (out of a maximum of 10).
Compared to conventional aerobic exercise, FES was associated with less favourable change in peak VO2 (-0.74mL/kg per minute, 95% CI -1.38 to -0.10, I2-0%; five trials). There was no difference in muscle strength (two trials). A small increase in six-minute walk test was neither statistically nor clinically significant (I2=41%, five trials).
Compared to control treatment, FES was associated with an increase in VO2 (2.78mL/kg per minute, 95% CI 1.44 to 4.13, I2=52%; two trials). Two trials reported that there was a statistically significant change in the six-minute walk test with FES, but not with the control treatments. No data were available for muscle strength.
The overall low quality of trials precluded planned sensitivity analyses. Use of random-effects models gave results similar to those in the main analyses (data not presented).