Tyler D. Martin

Running economy and maximal oxygen consumption after 4 weeks of oral Echinacea supplementation.

Abstract Whitehead, MT, Martin, TD, Scheett, TP, and Webster, MJ. Running economy and maximal oxygen consumption after 4 weeks of oral Echinacea supplementation. J Strength Cond Res 26(7): 1928–1933, 2012—The purpose of this investigation was to determine the effects of 4 weeks of oral Echinacea (ECH) supplementation on erythropoietin (EPO), red blood cell (RBC) count, running economy (RE), and V[Combining Dot Above]O2max. Twenty-four men aged 24.9 ± 4.2 years, height 178.9 ± 7.9 cm, weight 87.9 ± 14.6 kg, body fat 19.3 ± 6.5% were grouped using a double-blind design and self-administered an 8,000-mg·d−1 dosage of either ECH or placebo (PLA) in 5 × 400 mg × 4 times per day for 28 days. Blood samples were collected and analyzed for RBCs and EPO using automated flow cytometery and enzyme-linked immunosorbent assay. Maximal graded exercise tests (GXTs) were administered to measure V[Combining Dot Above]O2max, RE, and heart-rate responses. Analysis of variance was used to determine statistically significant differences (P ⩽ 0.05). The EPO increased significantly in ECH at 7 days (ECH: 15.75 ± 0.64, PLA: 10.01 ± 0.73 mU·ml−1), 14 days (ECH: 18.88 ± 0.71, PLA: 11.02 ± 0.69 mU·ml−1), and 21 days (ECH: 16.06 ± 0.55, PLA: 9.20 ± 0.55 mU·ml−1). V[Combining Dot Above]O2max increased significantly in ECH (ECH: 1.47 ± 1.28, PLA: −0.13 ± 0.52%). Running economy improved significantly in ECH as indicated by a decrease in submaximal V[Combining Dot Above]O2 during the first 2 stages of the GXT (stage 1: ECH −1.50 ± 1.21, PLA 0.60 ± 1.95%; stage 2: ECH −1.67 ± 1.43, PLA 0.01 ± 1.03%). These data suggest that ECH supplementation results in significant increases in EPO, V[Combining Dot Above]O2max, and running economy.

Crossvalidation of Two 20-M Shuttle-Run Tests for Predicting V[Combining Dot Above]O2max in Female Collegiate Soccer Players

Abstract Green, MS, Esco, MR, Martin, TD, Pritchett, RC, McHugh, AN, and Williford, HN. Crossvalidation of two 20-M shuttle-run tests for predicting V[Combining Dot Above]O2max in female collegiate soccer players. J Strength Cond Res 27(6): 1520–1528, 2013—The aim of this study was twofold: (a) to compare the maximal attained speed (MAS) from the 20-m shuttle (MST) and 20-m square-shuttle (SST) tests and (b) to crossvalidate 2 equations for predicting maximal oxygen consumption (V[Combining Dot Above]O2max) that were previously developed from MST and SST in a group of female collegiate soccer players. Thirty-nine subjects (age: 20.1 ± 1.5 years) participated in the study. A maximal graded exercise treadmill test was used to measure V[Combining Dot Above]O2max. In addition, V[Combining Dot Above]O2max was predicted from the MAS obtained during MST (predV[Combining Dot Above]O2maxMST) and SST (predV[Combining Dot Above]O2maxSST) using previously developed equations. Measured V[Combining Dot Above]O2max for the group was 44.2 ± 3.3 ml·kg−1·min−1. The MAS was 12.5 ± 0.6 km·h−1 for MST and 13.3 ± 0.8 km·h−1 for SST (p < 0.05). The prediction methods yielded a predV[Combining Dot Above]O2maxMST of 49.6 ± 3.9 ml·kg−1·min−1 and predV[Combining Dot Above]O2maxSST of 41.8 ± 3.1 ml·kg−1·min−1, which were significantly different from measured V[Combining Dot Above]O2max (p < 0.05). The validity statistics revealed the following constant error (CE), correlation coefficient (r), standard error of estimate (SEE), and total error (TE) for predV[Combining Dot Above]O2maxMST and predV[Combining Dot Above]O2maxSST: CE = 5.35 ± 3.83, r = 0.45 (p < 0.05), SEE = 2.97 ml·kg−1·min−1, TE = 6.39 ml·kg−1·min−1; and CE = −2.43 ± 2.49, r = 0.69 (p < 0.05), SEE = 2.39 ml·kg−1·min−1, TE = 3.43 ml·kg−1·min−1, respectively. Residual plots indicated no proportional bias for either prediction model. The results of this study suggest that female collegiate soccer players had a higher MAS from SST compared with that from MST. In addition, SST appeared to be a more accurate predictor of V[Combining Dot Above]O2max than MST in the group of athletes.

Effect of six weeks of oral echinacea purpurea supplementation on nitric oxide production

Background Echinacea purpurea, a purple coneflower plant of the compositae family (Asteraceae), is native to North America and commonly used as an herbal supplement to enhance immune function. Echinacea purpurea has been shown to stimulate macrophage activity which is a known stimulator of nitric oxide (NO) production. Echinacea purpurea supplementation (8,000 mg·d) in untrained (42.5 ± 1.6 mL·kg·min) males was shown to elicit a 63% increase (p < 0.05) in serum erythropoietin (EPO) following two weeks of supplementation. This is supported in part by earlier findings which indicated that four weeks of Echinacea purpurea supplementation demonstrated a non-significant increase in maximal oxygen uptake (VO2max). It is plausible that Echinaceainduced EPO production may stimulate physiological responses independent of and/or in addition to erythropoiesis. There is also evidence suggesting EPO has vasculo-protective effects including the activation of endothelial nitric oxide synthase (eNOS). Based on these findings, a proposed non-hematological response to the Echinacea-induced increase in EPO could be enhanced NO production. The purpose of this investigation was to determine whether six weeks of oral Echinacea purpurea supplementation augmented NO production as a result of an Echinacea-induced increase in EPO and/or Echinaceainduced macrophage activity.

Effect of Mouthguard Use on Metabolic and Cardiorespiratory Responses to Aerobic Exercise in Males

ABSTRACT Purpose: This study investigated the physiological effects of wearing a mouthguard during submaximal treadmill exercise. Method: Twenty-four recreationally active males (Mage = 21.3 ± 2.4 years, Mheight = 1.78 ± 0.06 m, Mweight = 81.9 ± 10.6 kg, Mbody mass index = 25.8 ± 3.4 kg·m−2) performed incremental, continuous exercise at 2, 4, 6, and 8 mph (3.2, 6.4, 9.7, 12.9 kph) for 5 min at each speed on a motor-driven treadmill on 2 separate occasions in a randomized, crossover, counterbalanced design while wearing or not wearing a self-adaptable “boil and bite” mouthguard. Respiratory rate (RR), tidal volume (VT), ventilation (VE), oxygen consumption (VO2), respiratory exchange ratio (RER), and heart rate (HR) data were averaged during the last 60 s of each exercise stage; blood lactate (LA) was measured before exercise and 3 min and 10 min following exercise. Results: Repeated-measures analysis of variance revealed that mouthguard use failed to alter the response of RR, VT, VE, VO2, RER, and HR to treadmill exercise (p > .05), although each variable did increase in magnitude as a result of increasing treadmill speed (p < .001). Although increasing to above resting values at both 3 min and 10 min (p < .001) after cessation of exercise, LA levels also displayed no differences with mouthguard use (p > .05). Conclusion: Despite predictable increases in respiratory, metabolic, and cardiovascular variables in response to incremental exercise, the presence of a mouthguard failed to affect the magnitude or nature of these physiological responses.