Oxidative stress is related to chronic disease in obesity, but is reversible with one or more interventions described above.

Mobility disability is becoming prevalent in the obese older population (> or = 60 years of age). We included a total of 13 cross-sectional and 15 longitudinal studies based on actual physical assessments of mobility in the obese older population in this review. We systematically examined existing evidence of which adiposity estimate best predicted mobility disability. Cross-sectional studies (82-4000 participants) showed poorer lower extremity mobility with increasing obesity severity in both men and women. All longitudinal studies (1-22 years) except for one, reported relationships between adiposity and declining mobility. While different physical tests made interpretation challenging, a consistent finding was that walking, stair climbing and chair rise ability were compromised with obesity, especially if the body mass index (BMI) exceeded 35 kg m(-2). More studies found that obese women were at an increased risk for mobility impairment than men. Existing evidence suggests that BMI and waist circumference are emerging as the more consistent predictors of the onset or worsening of mobility disability. Limited interventional evidence shows that weight loss is related with increased mobility and lower extremity function. Additional longitudinal studies are warranted that address overall body composition fat and muscle mass or change on future disability.

These data indicate high-intensity REX training was successful for improving BMD of the femoral neck in healthy elderly subjects. Also, these data suggest REX increased bone turnover, which over time may lead to further changes in BMD.

These data indicate that significant and similar improvements in strength, endurance, and stair climbing time can be obtained in older adults as a consequence of high- or low-intensity resistance exercise training. These findings may have an effect on how resistance exercise is prescribed to older adults.

VINCENT, HEATHER K., CHERYL BOURGUIGNON, AND KEVIN R. VINCENT. Resistance training lowers exercise-induced oxidative stress and homocysteine levels in overweight and obese older adults. Obesity. 2006;14: 1921-1930. Objective: To compare exercise-induced oxidative stress and levels of homocysteine and cholesterol in normalweight and overweight older adults after resistance exercise (RX). Research Methods and Procedures:This interventional study was conducted at a wellness center. Forty-nine older adults (age range, 60 to 72 years) were stratified by BMI (Ͻ25 kg/m 2 normal weight, Ն25 kg/m 2 overweight/obese) and then randomly assigned to either a control non-exercise group or an RX group. The RX group completed a 6-month training program. Exercise-induced lipid hydroperoxides (PEROXs) and thiobarbituric-reactive acid substances, homocysteine, lipoprotein a, cholesterol, and high-density lipoprotein cholesterol were measured before and after the 6-month RX program. Results: PEROXs and thiobarbituric-reactive acid substances were lower in both the overweight/obese and normal-weight RX-trained groups compared with control groups (p Ͻ 0.05). Homocysteine levels were lower in both overweight/obese and normal-weight RX groups compared with control groups (p Ͻ 0.05). Lipoprotein a, total cholesterol, and high-density lipoprotein cholesterol were not different in normal-weight and overweight/obese groups before or after RX. The change in muscle strength was correlated with homocysteine at 6 months (r ϭ Ϫ0.452, p Ͻ 0.05), whereas the change in PEROXs was correlated with the change in body fat (r ϭ Ϫ0.329). Discussion: To our knowledge, these data are the first to show that RX reduces exercise-induced oxidative stress and homocysteine regardless of adiposity, indicating that this protection can be afforded in an older, overweight/obese population as effectively as in healthy older adults. These data suggest that RX may afford some protection against emerging cardiovascular risk factors using a mode of exercise that supports body weight.

These findings indicate that increased circulating IGF-I may, at least in part, mediate increases in strength that result from resistance training.

Osteoarthritis (OA) is the most frequent cause of disability in the United States, with the medial compartment of the knee being the most commonly affected.1 The initiation and progression of knee OA is influenced by many factors including kinematics. In response to loading during weight bearing, cartilage in healthy knees demonstrates spatial adaptations in morphology and mechanical properties. These adaptations allow certain regions of the cartilage to respond to loading while other regions are less well suited to accommodate loading. Alterations in normal knee kinematics shift loading from those cartilage regions adapted for loading to regions less well suited. This leads to the initiation and progression of degenerative processes consistent with knee OA. Kinematic variables associated with the development, progression and severity of knee OA are the adduction moment (Madd) and tibiofemoral rotation. Due to its strong correlation with disease progression and pain, the peak Madd during gait has been identified as a target for treatment design. Gait modification offers a non-invasive option for seeking significant reductions. Gait modification has the potential to reduce pain and slow the progression of medial compartment knee OA.

Untrained individuals develop muscle soreness and increased serum creatine kinase (CK) activity in the blood after strenuous, unaccustomed exercise. An unpublished observation in our laboratory revealed that trained weightlifters also experience considerable soreness after unaccustomed exercise, but may not show a dramatic CK response. This study examined the CK and soreness responses to strenuous exercise in weightlifters (TR, n = 10) and untrained subjects (UTR, n = 10). Trained subjects had a minimum of three years weightlifting experience, and regularly performed squats and leg presses. Untrained subjects had not participated in any regular resistance exercise for the past three years. Following two acclimation sessions, subjects reported to the lab on seven consecutive days and on the tenth day after knee extensor exercise. Weight training sessions occurred on day 1 for the knee extensors (KE) and day 2 for the knee flexors (KF). The weight training consisted of these exercises (sets): squat (5), leg press (3), leg extension and lunge (3) for the KE, double leg curls (6), single leg curls (3), stiff-legged deadlifts (4, TR group only) for the KF at 12 RM for all exercises. To document the stress due to exercise, the loss in strength (isometric peak torque, IPT) was assessed on a Biodex isokinetic dynamometer. Maximal voluntary IPT of the KE at 90 degrees and the KF at 80 degrees decreased 17-30% with no significant differences between groups. Muscle soreness during simulated squat leg curl movement was assessed by a 100 mm visual analog scale (VAS). Average peak KE soreness was 76 mm for TR and 58 mm for UTR, KF soreness was 60 mm for TR and 47 mm for UTR post-exercise. Serum CK levels were significantly different between groups with a peak of 1349 IU for TR and 3272 IU for the UTR (p < 0.01). Although the TR group experienced greater soreness than the UTR, peak serum CK activity was significantly lower, suggesting that trained individuals can develop severe soreness without the same degree of increase in serum CK activity observed in untrained individuals.