Resistance exercise and physical performance in adults aged 60 to 83.

OBJECTIVES: This investigation examined the effect of 6 months of high- or low-intensity resistance exercise on muscular strength and endurance and stair climbing ability in adults aged 60 to 83. DESIGN: A randomized controlled trial. SETTING: University of Florida Center for Exercise Science. PARTICIPANTS: Sixty-two men and women completed the study protocol. Subjects were matched for strength and randomly assigned to a control (n = 16), low-intensity (LEX, n = 24), or high-intensity (HEX, n = 22) group. INTERVENTION: Six months of progressive, whole-body resistance training. Subjects trained at 50% of their one-repetition maximum (1RM) for 13 repetitions (LEX) or 80% of 1RM for eight repetitions (HEX) three times per week for 24 weeks using resistance machines. One set each of 12 exercises was performed. MEASUREMENTS: One-repetition maximum was measured for eight different exercises. Muscular endurance was measured using leg press and chest press machines. Low back strength was measured using a lumbar extension machine. Stair climbing ability was assessed as the time to ascend one flight of stairs. RESULTS: 1RM significantly increased for all exercises tested for the HEX and LEX groups (P < or =.050). The increases in total strength (sum of all eight 1RMs) were 17.2% and 17.8% for the LEX and HEX groups, respectively. Muscular endurance improved by 79.2% and 105.0% for the leg press, and 75.5% and 68.0% for the chest press for the LEX and HEX groups, respectively. The time to ascend one flight of stairs significantly decreased for both the LEX and HEX groups (P < or =.050). Lumbar extension strength increased by 62.6% and 39.5% for the LEX and HEX groups, respectively. CONCLUSIONS: 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.

Genotypic analysis of plasma HIV-1 RNA after influenza vaccination of patients with previously undetectable viral loads.

OBJECTIVE: In this study we evaluated the possibility that plasma viral load elevations secondary to influenza vaccination in HIV-1-seropositive individuals with previously undetectable viral loads (< 200 copies/ml) could develop resistance-bearing mutations in the viral reverse transcriptase (RT) and protease regions. METHODS: Thirty-four patients with undetectable viral burdens on highly active antiretroviral therapy (HAART) were evaluated for elevations in plasma viral load 2 and 4 weeks post-influenza vaccination. Plasma from patients whose viral load increased after vaccination was subject to genotypic resistance analysis by the line probe assay (LiPA) to determine whether primary resistance-bearing mutations developed during this period and at follow-up. Stored plasma was used to evaluate whether RT or protease mutations existed pre-vaccination. RESULTS: Seven out of 34 patients were found to experience elevations in their viral load after influenza vaccination. Two of the patients revealed evidence of primary RT or protease mutations not demonstrated in earlier pre-vaccination samples. One patient failed therapy after vaccination, and one patient revealed post-vaccination viral load elevations that eventually led to the progressive development of primary zidovudine mutations. CONCLUSION: Evidence is presented that supports the contention that a small subset of patients who experience viral load elevations after influenza vaccination can develop mutational changes in the RT region of the viral genome either acutely or after a failure of the viral load to return to undetectable levels.