Characteristics associated with responsiveness to isometric handgrip training in medicated hypertensive patients: secondary data analysis.

OBJECTIVE: Isometric handgrip training (IHT) has been shown to reduce blood pressure (BP) in hypertensive patients. However, factors that predict responsiveness to IHT are largely unknown. The aim of this study was to investigate the patient characteristics associated with the antihypertensive response to IHT using a recommended statistical approach for evaluating interindividual responses. METHODS: Data from four randomized controlled trials were joined, totaling 81 patients undergoing IHT (48.8% women; 60 ±â€Š11 years) and 90 control patients (45.6% women; 62 ±â€Š12 years). IHT consisted of 4 × 2 min isometric contractions at 30% of maximal voluntary contraction, performed three times/week for 8-12 weeks. BP was measured at baseline and following IHT and control interventions. The interindividual variation was assessed by the standard deviation of the individual responses (SDir), and linear regression analyses were conducted to explore response predictors. RESULTS: IHT significantly decreased both SBP (-5.4; 95% confidence interval (CI) -9.5 to -1.3 mmHg) and DBP (-2.8; 95% CI -5.1 to -0.6 mmHg). The interindividual variation of BP change was moderate for systolic (SDir = 5.2 mmHg, 0.30 standardized units) and low for diastolic (SDir = 1.7 mmHg, 0.15 standardized units). Sex, age, and BMI were not associated with the antihypertensive effect of IHT. However, a higher baseline SBP (b = -0.467, P < 0.001) and absence of dihydropyridine calcium channel blockers use (b = 0.340, P = 0.001) were associated with greater BP reductions. CONCLUSION: IHT reduced BP in medicated hypertensive patients regardless of age, sex, and BMI. Patients with a higher baseline SBP and those not prescribed dihydropyridine calcium channel blockers were more responsive to IHT.

Prediction of activity mode with global positioning system and accelerometer data.

PURPOSE: The primary aim of this pilot study was to assess how well the combination of global positioning system (GPS) and accelerometer data predicted different activity modes. METHODS: Ten adults (seven male, three female; 23-51 yr) simultaneously wore a GPS unit and accelerometer during bouts of walking, jogging/running, bicycling, inline skating, or driving an automobile. Discriminant function analysis was used to identify a parsimonious combination of variables derived from accelerometer counts and steps and GPS speed that best classified mode. A total of 29 bouts were used to develop this classification criterion. This criterion was validated using two datasets generated from the complete collection of minute-by-minute values from all bouts. RESULTS: Model development with "calibration" data showed that two accelerometer variables alone (median counts and steps) resulted in 26 of 29 bouts (90%) being correctly classified. Prediction of activity mode using counts and steps in a minute-by-minute "validation" dataset (N = 200) was 86.5%. Using three variables from the accelerometer and GPS (median counts, steps and speed) resulted in correct classification in 27 of 29 activity bouts in the "calibration" data (93%). In the "validation" dataset comprising 200 min, the combination of accelerometer counts and steps and GPS speed were able to correctly classify 91% of the observations. Walking and bicycling minutes were correctly classified most frequently (96%). In another "validation" dataset consisting of activity bouts, this combination of variables resulted in correct classification in 42 of 43 bouts (98%). CONCLUSION: This pilot study provides evidence that the addition of GPS to accelerometer monitoring improves physical activity mode classification to a small degree. Larger studies among free-living individuals and with an expanded range of activities are needed to replicate the current findings and further determine the merits of using GPS with accelerometers for mode identification.