Submitted on April 26, 2007
Accepted on October 5, 2007
Forearm blood flow follows work rate during submaximal dynamic forearm exercise independent of sex
Joaquin U. Gonzales1, Benjamin C. Thompson1, John R. Thistlethwaite1, Allison J. Harper1, and Barry W. Scheuermann1*
1 Kinesiology, The University of Toledo, Toledo, Ohio, United States
* To whom correspondence should be addressed. E-mail: barry.scheuermann{at}utoledo.edu.
To test the hypothesis that sex influences forearm blood flow (FBF) during exercise, 15 females and 16 males of similar age [females, 24.3 ± 4.0 (SD) vs. males, 24.9 ± 4.5 y] but different forearm muscle strength (females, 290.7 ± 44.4 vs. males, 509.6 ± 97.8 N; P < 0.05) performed dynamic handgrip exercise as the same absolute workload was increased in a ramp function (0.25 W·min-1). Task failure was defined as the inability to maintain contraction rate. Blood pressure and FBF were measured on separate arms during exercise by auscultation and Doppler ultrasound, respectively. Muscle strength was positively correlated with endurance time (r = 0.72, P < 0.01) such that females had a shorter time to task failure than males (450.5 ± 113.0 vs. 831.3 ± 272.9 s; P < 0.05). However, the percent of maximal handgrip strength achieved at task failure was similar between sexes (14% MVC). FBF was similar between females and males throughout exercise and at task failure (females, 13.6 ± 5.3 vs. males, 14.5 ± 4.9 ml·min-1·100ml-1). Mean arterial pressure was lower in females at rest and during exercise, thus calculated forearm vascular conductance (FVC) was higher in females during exercise but similar between sexes at task failure (females, 0.13 ± 0.01 vs. males, 0.12 ± 0.04 ml·min-1·100ml-1·mmHg-1). In conclusion, the similar FBF during exercise was achieved by a higher FVC in the presence of a lower MAP in females than males. Still, FBF remained coupled to work rate during exercise irrespective of sex.
