Effect of compression stockings on physiological responses and running performance in division III collegiate cross-country runners during a maximal treadmill test.

There is a growing trend for runners to use compression stockings (CS) to improve performance. The purpose of this study was to determine the effect of CS on physiological variables associated with running performance. Participants were 10 NCAA division III cross-country runners. The study used a randomized, crossover design with 2 conditions (with CS and without CS). Both conditions consisted of a maximal treadmill test that involved 3-minute stages of increasing speed and incline, separated by a minute and one-half walking recovery stage. Seven days later, the participants repeated the maximal test but switched CS condition. Heart rate, blood lactate (BLa), blood lactate threshold, maximal oxygen consumption (VO2max), respiratory exchange ratio, rating of perceived exertion, and time to fatigue were measured. Before and during the maximal treadmill tests, the variables showed no significant difference (p ≤ 0.05) between the CS conditions. Blood lactate was lower while wearing CS when measured during recovery at the 1-minute (CS = 13.3 ± 2.9 mmol · L(-1), non-CS = 14.8 ± 2.8 mmol · L(-1), p = 0.03) and the 5-minute (CS = 11.0 ± 2.7 mmol · L(-1), non-CS = 12.8 ± 2.8 mmol · L(-1), p = 0.02) periods. Time to fatigue was longer without CS (CS = 23.570 ± 2.39 minutes, non-CS = 23.93 ± 2.49 minutes, p = 0.04). These findings suggest that CS may not improve running performance, but could lend credence to certain manufacturers' claims of improved recovery through lower BLa values after exercise.

Metabolic syndrome status changes with fitness level change: a retrospective analysis.

BACKGROUND: Cardiorespiratory fitness level is inversely related to the incidence of Metabolic Syndrome (MetS). This study examined the effects of changes in cardiorespiratory fitness level on MetS status. METHODS: Male and female participants in a health enhancement program (n = 212) were clinically examined for changes in their MetS status and estimated aerobic capacity over a 3-year period. Two physical examinations, each including a maximal treadmill stress test, occurred within this time frame. Participants were divided into three groups: Group 1 (n = 103) was composed of individuals who presented with MetS at exam 1 and reversed their MetS disease status by exam 2; Group 2 (n = 75) members presented with MetS at both exams; and Group 3 (n = 34) individuals were MetS-free at exam 1 but acquired MetS by exam 2. The relationships between MetS clinical characteristics at exam 1 and exam 2 and changes in graded exercise test (GXT) duration were contrasted for the three groups. RESULTS: GXT duration, estimated aerobic capacity (VO(2) max), and MetS characteristics improved significantly in Group 1 (P < 0.01). Group 2 individuals also increased GXT duration (P < 0.05) but showed only nonsignificant improvements (P > 0.05) in clinical characteristics. Group 3 members declined in most MetS characteristics and in estimated VO(2) max (P < 0.05). CONCLUSIONS: Increases in GXT duration accompanied MetS reversal while declines in GXT duration occurred with MetS acquisition. On an individual basis, these changes in GXT duration may be an indicator of disease status.

Longitudinal modeling of the relationship between age and maximal heart rate.

PURPOSE: Maximal heart rate (HRmax)-prediction equations based on a person's age are frequently used in prescribing exercise intensity and other clinical applications. Results from various cross-sectional studies have shown a linear decrease in HRmax during exercise with increasing age. However, it is less well established that longitudinal tracking of the same individuals' HRmax as they age exhibits an identical linear relationship. This study examined the longitudinal relationship between age and HRmax during exercise. METHODS: A retrospective analysis of maximal graded exercise test (GXT) results for members participating in a university-based health-assessment/fitness center between 1978 and 2003 was undertaken in 2006. Records were examined from individuals (N = 132) of both sexes who represented a broad range of age and fitness levels and who had multiple GXT (total N = 908) conducted over 25 years. HRmax-prediction equations based on participants' age and HRmax elicited during the tests were developed using a linear mixed-models statistical analysis approach. RESULTS: Clinical measurements obtained during the administration of the GXT included in this longitudinal study resulted in the generation of a univariate prediction model: HRmax = 207 - 0.7 x age. Model parameters were highly statistically significant (P < 0.001). CONCLUSIONS: The relationship between age and HRmax during exercise developed in this longitudinal study has resulted in a prediction equation appreciably different from the conventional HRmax formula (220 - age) often used in exercise prescription, and it confirms findings from recent cross-sectional investigations of HRmax.

Reversal of metabolic syndrome characteristics.

BACKGROUND: Metabolic syndrome (MetS) is a constellation of three or more clinical health abnormalities from a list of five and, therefore, can vary significantly in its profile. Successful intervention strategies for preventing or resolving individuals' MetS may benefit from better understanding how specific risk factor profiles influence improvement in syndrome status. METHODS: A retrospective analysis of clinical records for members participating in a university-based health assessment/fitness center between 1978 and 2003 was undertaken in 2005. First-year and second-year measures of body mass index, triglycerides, high-density lipoproteins, fasting blood glucose, and blood pressure were compared. Prevalence of individual MetS risk markers, as well as deviation from cut-point levels, were compared in members with and without the syndrome and in subgroups of those whose MetS status changed between the two examinations. RESULTS: Of the 878 members analyzed, 133 (15%) presented with metabolic syndrome at first visit. Within 2 years of participating in a health assessment/fitness center, 42% of the members resolved their MetS status. Elevated triglycerides differentially characterized those participants who did not improve their MetS status, since that risk marker was not prevalent in the reversal group, but was 86% prevalent in the nonreversal group. For those who resolved their MetS status, there was a 33% improvement in triglycerides level. CONCLUSIONS: While MetS resolution was achieved within 2 years for many participants in this study, it is likely that customized treatment interventions are necessary for those individuals with elevated triglycerides, the chief abnormality for those who did not resolve.