main effect for treadmill mode for HR ( p = .011) and EE ( p = .025) only. There were no differences in EE between specific treadmill modes when collapsed across speeds. Table 2 Cardiometabolic Responses at Rest and During Treadmill Exercise Treadmill stage Variable Treadmill mode Rest 1.0 mph 1
Brandon R. Rigby, Ronald W. Davis, Marco A. Avalos, Nicholas A. Levine, Kevin A. Becker and David L. Nichols
Takeshi Kokubo, Yuta Komano, Ryohei Tsuji, Daisuke Fujiwara, Toshio Fujii and Osamu Kanauchi
, Japan); mice in the LC-Plasma group were fed AIN-93G + 0.029% LC-Plasma; mice in the LGG group received AIN-93G + 0.029% LGG, for 4 weeks. Exercise acclimation was performed 1 week before the exercise experiment. After 4 weeks, the mice underwent the loaded treadmill exercise, as described in “exercise
Gabrielle Ringenberg, Jill M. Maples and Rachel A. Tinius
exercise capacity using a submaximal treadmill exercise test among OB women. Our finding was consistent with previous research using submaximal and maximal cycle protocols ( Wisen, Mao, Christiansen, Saltin, 2015 ). They found the Astrand submaximal cycle test to be a poor predictor of fitness levels among
Nicholas J. Walters and David A. Brodie
The purpose of this study was to assess the validity of data derived from the Kenz calorie counter during progressive, incremental treadmill exercise. Direct comparisons were made with calories calculated from on-line gas analysis. The subjects were 18 adults, 18 postadolescent children, and 24 preadolescent children. Linear regression (r 2 > .95) showed a progressive deviation away from a 1:1 relationship between Kenz data and V̇O2 data with increasing age of subject which remained when standardized to kcal · kg−1 body mass or kcal · m−2 · hour−1. The Kenz calorie counter, after applying an age group correction factor, can thus be used as a suitable analog for measured energy expenditure.
Abbass Ghanbari-Niaki, Rozita Fathi, Sayed Alireza Hossaini Kakhak, Zhara Farshidi, Sara Barmaki, Fatemeh Rahbarizadeh and Robert R. Kraemer
Agouti-related protein (AGRP) is an orexigenic peptide secreted from the arcuate nucleus (ARC) of the hypothalamus. AGRP increases food intake and plays a role in energy balance, adiposity, weight gain, and growth-hormone release. The objective of the current study was to examine the effects of running exercise on resting hepatic, fundus, and pancreas AGRP mRNA expression, as well as liver glycogen and ATP contents, using a rat model. Twenty adult male Wistar rats (12–14 wk old, 200–220 g) were randomly assigned to control (n = 10) and training (n = 10) groups. The training group was exercised for 8 wk on a motor-driven treadmill (26 m/min, 0% grade, 60 min, 5 d/wk). Twenty-four hours before sacrifice the rats were further divided into fed control (FEC), fed trained (FET), fasted control (FAC), and fasted trained (FAT) groups. The liver, fundus, and pancreas were excised and frozen in liquid nitrogen for later analysis. Results demonstrated that 8 wk of treadmill exercise reduced hepatic but not fundus and pancreatic AGRP expression and enhanced glycogen and ATP concentrations (p < .001) in trained-rat liver, whereas fasting lowered liver glycogen and ATP levels and increased hepatic AGRP mRNA expression in nonexercising controls. Data indicate that both treadmill-exercise-induced decrease and fast-induced increase in rat liver AGRP expression might depend on liver glycogen content as an important source for energy provision.
Alan J. Ryan, Amy E. Navarre and Carl V. Gisolfi
These studies were done to determine the effect of carbonation and carbohydrate content on either gastric emptying or ad libitum drinking during treadmill exercise in the heat. Four test drinks were used: a 6% carbohydrate, noncarbonated; a 6% carbohydrate, carbonated; a 10% carbohydrate, noncarbonated; and a 10% carbohydrate, carbonated drink. For gastric emptying studies, subjects completed four 1-hr treadmill runs in the heat. They were given 400 mL of test drink at 0 rnin and 200 mL at 15, 30, and 45 min of exercise. For ad libitum drinking studies, subjects completed four 2-hr treadmill runs in the heat. Gastric residual volumes were similar during the four 1-hr runs. During the 2-hr runs, ad libitum drinking of the four beverages was also similar. Mean values for sweat rate, percentage of body weight lost, and percentage of fluid replaced by ad libitum drinking were similar for the four trials. Similar changes in heart rate, rectal temperature, and ratings of perceived exertion were also observed during the four 2-hr treadmill runs. We conclude that the presence of carbonation in a carbohydrate drink did not have a significant effect on either gastric emptying or ad libitum drinking.
James Faulkner, Alexis R. Mauger, Brandon Woolley and Danielle Lambrick
To assess the utility of a self-paced maximal oxygen uptake (VO2max) test (SPV) in eliciting an accurate measure of VO2max in comparison with a traditional graded exercise test (GXT) during motorized treadmill exercise.
This was a cross-sectional experimental study whereby recreationally trained men (n = 13, 25.5 ± 4.6 y) completed 2 maximal exercise tests (SPV, GXT) separated by a 72-h recovery period.
The GXT was continuous and incremental, with prescribed 1-km/h increases every 2 min until the attainment of VO2max. The SPV consisted of 5 × 2-min stages of incremental exercise, which were self-selected and adjusted according to 5 prescribed RPE levels (RPE 11, 13, 15, 17, and 20).
Although no significant differences in VO2max were observed between the SPV and GXT (63.9 ± 3.3 cf 60.9 ± 4.6 mL · kg−1 · min−1, respectively, P > .05), the apparent 4.7% mean difference may be practically important. The 95% limits-of-agreement analysis was 3.03 ± 11.49 mL · kg−1 · min−1. Therefore, in the worst-case scenario, the GXT may underestimate measured VO2max as ascertained by the SPV by up to 19%. Conversely, the SPV could underestimate the GXT by 14%.
The current study has shown that the SPV is an accurate measure of VO2max during exercise on a motorized treadmill and may provide a slightly higher VO2max value than that obtained from a traditional GXT. The higher VO2max during the SPV may be important when prescribing training or monitoring athlete progression.
Fleur E. Horner, Joanna Slade and James L. J. Bilzon
Accelerometers are commonly used to quantify physical activity. There is no accordance regarding the most suitable attachment site. This study assessed the reliability and validity of accelerometer output (PAC) from 2 placements.
26 females (age 20.4 ± 1.3 years, body mass 62.7 ± 6.8 kg) twice performed a 16-minute treadmill protocol comprising 4 stages (4, 5, 8, 10 km·hr−1) and oxygen uptake (VO2) was calculated. Participants wore an accelerometer at the hip and lower back. Skinfold thickness was measured at 8 sites. Reliability was assessed using coefficients of variation (CVintra). Interactions between placement, velocity and PAC (counts·5s−1) were assessed using analysis of covariance. PAC-VO2 associations were assessed using multiple regression.
Hip and back placements returned similar reliability (CVintra = 3.0% and 2.8% respectively). Hip PAC were higher (P < .01) during walking with no differences observed during running. Indices of adiposity were related to hip PAC. Regression revealed hip and back PAC as significant predictors of VO2. Back PAC was the least variable. Hip skinfold thickness explained 15% additional variance in VO2 to PAC with reduced standard error.
The lower back is a more suitable accelerometer placement for young, active females during treadmill exercise.
Karsten Koehler, Thomas Abel, Birgit Wallmann-Sperlich, Annika Dreuscher and Volker Anneken
Inactivity and overweight are major health concerns in children and adolescents with disabilities. Methods for the assessment of activity and energy expenditure may be affected negatively by the underlying disability, especially when motor function is impaired. The purpose of this study was to assess the validity of the SenseWear Armband in adolescents with cerebral palsy and hemiparesis.
Ten volunteers (age: 13.4 ± 1.6 years) were equipped with SenseWear Armbands on the hemiparetic and nonhemiparetic side of the body. Energy expenditure was measured at rest and during treadmill exercise (speed range: 0.85 to 2.35 m/s). Indirect calorimetry served as independent reference method.
The mean error was between −0.6 and 0.8 kcal/min and there were no significant differences between SenseWear and indirect calorimetry at any speed. Differences between body sides in expenditure (mean: −0.2 to 0.0 kcal/min) and step count (mean: −3.4 to 9.7 steps/min) were not significant.
The validity of the SenseWear Armband does not appear to be negatively affected by cerebral palsy during laboratory treadmill exercise. Future field studies are necessary to assess the validity and practicability of energy expenditure and physical activity assessment in children and adolescents with physical disabilities.
Peter Brubaker, Cemal Ozemek, Alimer Gonzalez, Stephen Wiley and Gregory Collins
Underwater treadmill (UTM) exercise is being used with increased frequency for rehabilitation of injured athletes, yet there has been little research conducted on this modality.
To determine the cardiorespiratory responses of UTM vs land treadmill (LTM) exercise, particularly with respect to the relationship between heart rate (HR) and oxygen consumption (VO2).
Design and Setting:
This quantitative original research took place in sports medicine and athletic training facilities at Wake Forest University.
11 Wake Forest University student athletes (20.8 ± 0.6 y, 6 women and 5 men).
All participants completed the UTM and LTM exercise-testing protocols in random order. After 5 min of standing rest, both UTM and LTM protocols had 4 stages of increasing belt speed (2.3, 4.9, 7.3, and 9.6 km/h) followed by 3 exercise stages at 9.6 km/h with increasing water-jet resistance (30%, 40%, and 50% of jet capacity) or inclines (1%, 2%, and 4% grade).
Main Outcome Measures:
A Cosmed K4b2 device with Polar monitor was used to collect HR, ventilation (Ve), tidal volume (TV), breathing frequency (Bf), and VO2 every minute. Ratings of perceived exertion (RPE) were also obtained each minute.
There was no significant difference between UTM and LTM for VO2 at rest or during any stage of exercise except stage 3. Furthermore, there were no significant differences between UTM and LTM for HR, Ve, Bf, and RPE on any exercise stage. Linear regression of HR vs VO2, across all stages of exercise, indicates a similar relationship in these variables during UTM (r = .94, y = .269x − 10.86) and LTM (r = .95, y = .291x − 12.98).
These data indicate that UTM and LTM exercise elicits similar cardiorespiratory responses and that HR can be used to guide appropriate exercise intensity for college athletes during UTM.