Background: Fluctuations in 24-hour cardiovascular hemodynamics, specifically heart rate (HR) and blood pressure (BP), are thought to reflect autonomic nervous system (ANS) activity. Persons with spinal cord injury (SCI) represent a model of ANS dysfunction, which may affect 24-hour hemodynamics and predispose these individuals to increased cardiovascular disease risk. Objective: To determine 24-hour cardiovascular and ANS function among individuals with tetraplegia (n = 20; TETRA: C4-C8), high paraplegia (n = 10; HP: T2-T5), low paraplegia (n = 9; LP: T7-T12), and non-SCI controls (n = 10). Twenty-four-hour ANS function was assessed by time domain parameters of heart rate variability (HRV); the standard deviation of the 5-minute average R-R intervals (SDANN; milliseconds/ms), and the root-mean square of the standard deviation of the R-R intervals (rMSSD; ms). Subjects wore 24-hour ambulatory monitors to record HR, HRV, and BP. Mixed analysis of variance (ANOVA) revealed significantly lower 24-hour BP in the tetraplegic group; however, BP did not differ between the HP, LP, and control groups. Mixed ANOVA suggested significantly elevated 24-hour HR in the HP and LP groups compared to the TETRA and control groups (P < 0.05); daytime HR was higher in both paraplegic groups compared to the TETRA and control groups (P < 0.01) and nighttime HR was significantly elevated in the LP group compared to the TETRA and control groups (P < 0.01). Twenty-four-hour SDANN was significantly increased in the HP group compared to the LP and TETRA groups (P < 0.05) and rMSSD was significantly lower in the LP compared to the other three groups (P < 0.05). Elevated 24-hour HR in persons with paraplegia, in concert with altered HRV dynamics, may impart significant adverse cardiovascular consequences, which are currently unappreciated.

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Recent investigations with young, healthy adult subjects suggest that static stretching before activity decreases performance and should, therefore, be avoided. The purpose of this study was to assess the effects of an acute static stretching protocol on balance and jump/hop performance in active middle-aged adults. Ten subjects (6 men and 4 women aged 40-60 yr) from a martial arts school volunteered to take part in this research study. This was a repeated measures design. Subjects who stretched for 10 minutes using a 30-second hold during 1 session sat quietly for 10 minutes during the alternate session. Sessions were randomly assigned. The following dependent variables were compared: Dynamic Stability Index (DSI) for single-leg dynamic balance (smaller DSI = improved balance); distances for broad jump, single hop, triple hop, and crossover hop; elapsed time for a 6-m timed hop. Group means for balance were significantly different between the stretch and no-stretch conditions (3.5 +/- 0.7 vs. 4.3 +/- 1.4 DSI, respectively; p < 0.05). No significant differences were found between the group means of the stretch and no-stretch conditions for the dependent measures of broad jump, single hop, triple hop, crossover hop, and 6-m timed hop performance. Ten minutes of acute static stretching enhances dynamic balance and does not affect jump/hop performance in active middle-aged adults. Static stretching should be included before competition and before exercise in fitness programs of active middle-aged adults.

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