The authors found a difference between W@ and W@ sessions for mean ( standard deviation ) ventilation ( @ % -LSB- @ % -RSB- and @ % -LSB- @ % -RSB- of maximal ventilation , respectively ; P = @ ) and a small difference for mean ( standard deviation ) heart rate ( @ -LSB- @ -RSB- and @ -LSB- @ -RSB- beats/min , respectively ; P < @ ) .