Table 2

Magnetic resonance spectroscopy variables measured before, during, and after treatment with citrulline/malate

BeforeDuringAfter
Values are reported as mean (SE). PCr(%) refers to the amount of phosphocreatine consumed at the end of exercise. Viex and Virec indicate respectively the initial rate of PCr consumption during exercise and synthesis during the recovery period. Δ[PCr]/power and ΔpH/power were calculated as indicated in the Methods section. EC refers to the total energy cost. As indicated in the text, before and during refer to extrema of variables calculated before and during the treatment.
*Significantly different from measurements before and after the treatment period.
Rest
    [PCr] (mM)37.8 (0.3)37.5 (0.3)37.7 (0.5)
    pH7 (0.01)7 (0.01)6.99 (0.01)
Exercise
    Initial phase of exercise
        EC (mM/min/W)22.8 (2.1)19.6 (1.6)21 (1.7)
        Viex (mM/min)46.7 (5.3)57.2 (3.9)41.9 (4.4)
    End of exercise
        PCr(%)69 (3.8)72 (2)61 (3)
        pH6.57 (0.03)6.58 (0.04)6.49 (0.05)
        Power (W)1.7 (0.1)2 (0.1)*1.7 (0.08)
        pH6.57 (0.03)6.58 (0.04)6.49 (0.05)
        Δ[PCr]/power (mM PCr/W)14.9 (1.2)12.4 (0.8)14.1 (0.7)
        ΔpH/power (pH unit/W)0.29 (0.05)0.24 (0.02)*0.3 (0.03)
        Rate of oxidative ATP production (%EC)54 (12)74 (4)*45 (6)
Recovery
    Virec (mM/min)16.9 (2.9)24.2 (3.2)*16.4 (1.9)