Ronald L. Wiley

Generation of reactive oxygen species after exhaustive aerobic and isometric exercise

UNLABELLED Many studies have implicated elevated oxygen consumption (VO2) associated with aerobic exercise as contributing to oxidative stress. Only a few studies have investigated nonaerobic exercise and its relation to pro-oxidant and antioxidant activities. PURPOSE The purpose of this study was to compare biomarkers of oxidative stress: lipid peroxidation, protein oxidation, and total antioxidants in blood after exhaustive aerobic (AE) and nonaerobic isometric exercise (IE). METHODS Blood samples were collected from 12 subjects who performed a maximum AE and IE test and were analyzed for thiobarbituric acid (TBARS), carbonyls, lipid hydroperoxides (LH), and oxygen radical absorbance capacity (ORAC). RESULTS VO2 increased 14-fold with AE compared with 2-fold with IE. Protein carbonyls increased 67% (P < 0.05) pre- to immediately and 1 h post-AE, and 12% pre- to immediately post-IE and returned to baseline 1 h post-IE. TBARS did not increase significantly with either treatment. LH increased 36% above rest during IE compared with 24% during AE (P < 0.05). ORAC increased 25% (P < 0.05) pre- to post-AE, compared with 9% (P < 0.05) pre- to post-IE. CONCLUSION There was evidence of oxidative stress after both exhaustive aerobic and isometric exercise. Lipid hydroperoxides, protein carbonyls, and total antioxidants increased after both IE and AE. Due to the different metabolic demands of aerobic and isometric exercise, we can rule out a mass action effect of VO2 as the sole mechanism for exercise-induced oxidative stress.

Isometric Training Lowers Resting Blood Pressure and Modulates Autonomic Control

PURPOSE This study examined the effects of isometric handgrip training on resting arterial blood pressure, heart rate variability, and blood pressure variability in older adults with hypertension. METHODS Nine subjects performed four 2-min isometric handgrip contractions at 30% of the maximum voluntary contraction force, 3 d.wk(-1) for 10 wk, and eight subjects served as controls. RESULTS After training, there was a significant reduction in resting systolic pressure and mean arterial pressure. In addition, power spectral analysis of heart rate variability demonstrated that the low frequency: high frequency area ratio tended to decrease. CONCLUSIONS It is concluded that isometric training at a moderate intensity elicits a hypotensive response and a simultaneous increase in vagal modulation in older adults with hypertension.

Consumption of green tea protects rats from exercise-induced oxidative stress in kidney and liver

Abstract The effects of green tea on biomarkers of exercise-induced oxidative status were measured in young male Sprague-Dawley rats. Rats (n = 12) drank green tea or water ad lib for 6.5 weeks. Half of each group was sacrificed at rest, and the other half ran 25 m/min at 0% grade for approximately 30 min immediately before sacrifice. Green tea had no effect on resting heart rate, blood pressure, body weight, cholesterol, or triglycerides. Tea consumption had a mild influence on total plasma antioxidants, heart glutathione, and plasma ascorbic acid. Exercise had a major impact on malonaldehyde (MDA) equivalents in kidney (+290%, p = 0.0001), and to a lesser extent, liver (+81%, p = 0.18) in rats that drank water. In contrast, kidney MDA equivalents were unchanged by exercise in rats that drank green tea. Green tea may have selective protective effects within the body, especially on the kidney.

Exercise improves biomarkers of health and stress in animals fed ad libitum

Voluntary and forced exercise decrease morbidity and mortality in laboratory animals. Caloric restriction has similar effects on health and unique benefits on life span. Nonetheless, in most experiments, animals do not have access to physical activity and are fed ad libitum (AL). We hypothesized that with regular access to either unlimited running wheel exercise (EX) or limited physical activity (PA), key biomarkers of health would be enhanced enough to counter some consequences of a sedentary AL lifestyle. This 16-month study compared body weight, tumor number and size, tissue lesions, oxidative stress, and reactive stress in (1) sedentary animals with no access to physical activity (SED); (2) animals with access to hour-long, twice weekly activity in a large box (PA); and (3) animals with access every other day to a running wheel (EX). At the end of the study, EX body weight was 8-9% lower than PA and SED. In addition, EX had no kidney lesions versus 50% in PA and SED, and had smaller tumor size (10+/-2 vs. 14+/-4 and 30+/-4 mm). Exhaustive exercise lowered glutathione/oxidized glutathione ratio in EX and PA, but in SED, the ratio was depressed even in resting animals. In all treatments, prolactin (PRL) levels were lower in resting animals than in acutely exercised animals. In conclusion, EX had the most favorable health biomarkers while SED had the least. PA did not confer gross health benefits different than the SED group, but was biochemically more similar to EX animals.

Cardiopulmonary responses to combined rhythmic and isometric exercise in humans.

SummaryA rhythmic (R) and an isometric (I) exercise were performed separately and in combination to assess their additive effects on arterial systolic (Pas) and diastolic (Pad) blood pressures, heart rate (fc), and minute ventilation (VI). The isometric effort consisted of a 40% maximal voluntary handgrip contraction (MVC) performed for a duration of 80% of a previously determined 40% MVC fatiguing effort. The R effort consisted of a 13-min cycle effort at 75% maximum oxygen consumption (VO2maX). For the combined efforts, I was performed starting simultaneously with or ending simultaneously with R. Data on nine subjects yield statistically significant evidence (P<0.05) that the effects of I and R are not additive for the following three cases: (1)Pas when I and R are ended simultaneously (I alone=4.9, SEM 0.5 kPa increase; R alone=no significant change from steady state; I+R=1.2, SEM 0.4 kPa increase), (2)Pad when I and R are started simultaneously (I alone=4.1, SEM 0.4 kPa increase; R alone=0.7, SEM 0.3 kPa decrease; I+R=1.9, SEM 0.4 kPa increase), and (3)Pad when I and R are ended simultaneously (I alone=4.1, SEM 0.4 kPa increase; R alone=0.3, SEM 0.5 kPa decrease; I+R=0.8, SEM 0.3 kPa increase). For all other variables and cases, there is not sufficient evidence to conclude that the effects of I and R are not additive. We conclude that R and I exercises do not invariably produce strictly additive cardiopulmonary responses. When R and I exercises are started simultaneously, however,Pas,fc, andVI are additive. Finally, cardiopulmonary responses to I efforts superimposed on steady-state 75%VO2max R efforts suggest that cardiopulmonary controls already established during R efforts attenuate responses to the I effort.

Transient and steady-state cardiopulmonary responses to combined rhythmic and isometric exercise

SummaryThe transient and steady-state cardiopulmonary responses to combined rhythmic (R) and isometric (I) exercise were examined in nine subjects. Isometric exercise at 30% maximal voluntary contraction (MVC) was started 1.5 min prior to either a 50% or 75% maximal oxygen uptake (

Short-term isometric exercise reduces systolic blood pressure in hypertensive adults: Possible role of reactive oxygen species

\dot VO_{2 max}

Afferent Inputs to Breathing: Respiratory Sensation

) cycle ride and continued for 1.5 min into the 10-min R. Systolic (Pas) and diastolic (Pad) blood pressure, heart rate (fc), inspired ventilation volumes (