Gina M. Morss

Field testing of physiological responses associated with Nordic Walking

Abstract This study compared the physiological responses (oxygen consumption and energy expenditure) of Nordic Walking to regular walking under field-testing conditions. Eleven women (M age = 27.1 years, SD = 6.4) and 11 men (M age = 33.8 years, SD = 9.0) walked 1,600 m with and without walking poles on a level, 200-m track. For women, Nordic Walking resulted in increased oxygen consumption (M = 14.9 ml·kg1·min−1 , SD = 3.2 vs. M = 17.9 ml·kg1·min−1 , SD = 3.5; p < .001), caloric expenditure (M = 4.6 kcal·min−1 , SD = 1.2 vs. M = 5.4 kcal·min−1 , SD = 1.2; p < .001), and heart rate (M = 113.7 bpm, SD = 12.0 vs. M = 118.7 bpm, SD = 14.8; p < .05) compared to regular walking. For men, Nordic Walking resulted in increased oxygen consumption (M = 12.8 ml·kg1·min−1 , SD = 1.8 vs. M = 15.5, SD = 3.4 ml·kg1·min−1; p < .01), caloric expenditure (M = 5.7 kcal·min−1 , SD = 1.3 vs. M = 6.9 kcal·min−1 , SD = 1.8; p < .001), and heart rate (M = 101.6 bpm, SD = 12.0 bpm vs. M = 109.8 bpm, SD = 14.7; p < .01) compared to regular walking. Nordic Walking, examined in the field, results in a significant increase in oxygen use and caloric expenditure compared to regular walking, without significantly increasing perceived exertion.

Laboratory calibration and validation of the Biotrainer and Actitrac activity monitors.

PURPOSE The Biotrainer and Actitrac activity monitors (IM Systems) offer potential research advantages over existing accelerometry-based activity monitors, but they have not been tested under controlled conditions. The purpose of this study was to develop and test laboratory-based prediction equations for both monitors to estimate energy expenditure (EE) for walking/running movements. METHODS Participants in the study wore a Biotrainer and Actitrac monitor on both hips and completed three paced bouts on the treadmill (3, 4, and 6 mph for 6 min each). Metabolic data collected using an indirect calorimetry system were used as the criterion measure. Multiple regression techniques were performed to develop prediction equations, and these equations were then applied to data from a separate sample for cross-validation purposes. Reliability was also examined. RESULTS The correlations between the raw counts from each monitor and the measured metabolic variables ranged from r = 0.74-0.88 for the Biotrainer and from r = 0.81-0.91 for the Actitrac. The equations predicting EE (kcal x min-1) from counts yielded strong validation results for both the Biotrainer (R2 = 0.88, SEE = 1.47) and the Actitrac (R2 = 0.91, SEE = 1.24). When used on the cross-validation sample, the correlations between measured and predicted EE were r = 0.93 (Biotrainer) and r = 0.94 (Actitrac). Intraclass reliability coefficients computed between the left and right monitors ranged from 0.60 to 0.71 (Biotrainer) and 0.80 to 0.87 (Actitrac). When the equation developed from one side was applied to data from the monitor on the other side, there were no significant differences in predicted and measured EE for most comparisons. CONCLUSION The results support the validity of Biotrainer and Actitrac monitors for estimating energy expenditure under controlled conditions.

Effects of a commercial herbal-based formula on exercise performance in cyclists

INTRODUCTION/PURPOSE We examined the effects of a commercially marketed herbal-based formula purported to increase endurance on oxygen consumption (VO2) in 17 competitive category III/IV amateur cyclists [mean (SEM) age: 31.1 (1.8) yr; height: 178.5 (1.8) cm; weight: 77.1 (1.6) kg]. METHODS Each cyclist participated in two (pre/post) cycling tests progressing 25 W.4 min(-1) starting at 100 W administered in a randomized, placebo-controlled, double-blind fashion. The second trial was performed 14 d after the ingestion of a manufacturer recommended loading phase (4 d x 6 caps.d(-1)) and a maintenance phase (11 d x 3 caps.d(-1)). Three treatment capsules contained 1000 mg of Cordyceps sinensis (CS-4) and 300 mg Rhodiola rosea root extract as the primary ingredients; 800 mg of other ingredients included calcium pyruvate, sodium phosphate, potassium phosphate, ribose, and adenosine and 200 mcg of chromium. RESULTS Using a 2 x 2 ANOVA, we observed no significant treatment effect for any between or within group variables including peak VO2 [treatment 4.14 (0.2) L.min(-1); placebo 4.10 (0.2) L.min(-1)], time to exhaustion [treatment 38.47 (1.7) min; placebo 36.95 (1.8) min], peak power output (PO) [treatment 300.00 (12.1) W; placebo 290.63 (12.9) W], or peak heart rate. We also observed no differences for any subpeak exercise variable including the PO eliciting 2 mmol.L(-1) blood lactate (BLa) [treatment 201.00 (18.1) W; placebo 167.50 (19.2) W] and 4 mmol.L(-1) BLa [treatment 235.88 (15.8) W; placebo 244.78 (14.9) W], ventilatory threshold, respiratory compensation point, or Vo2 L.min(-1) gross efficiency at each stage. CONCLUSION A 2-wk ingestion schema of a commercial herbal-based formula is insufficient to elicit positive changes in cycling performance.