.2) Weekly distance, km 41.2 (15.6) Self-selected running speed, km/h 10.4 (1.2) Note: Values are expressed as mean (SD) except as indicated in first row. Study Procedures Participants performed a single testing session of treadmill running on a dual-belt instrumented treadmill (AMTI, Watertown, MA). A
Heather K. Vincent, Laura A. Zdziarski, Kyle Fallgatter, Giorgio Negron, Cong Chen, Trevor Leavitt, MaryBeth Horodyski, Joseph G. Wasser and Kevin R. Vincent
Brandon R. Rigby, Ronald W. Davis, Marco A. Avalos, Nicholas A. Levine, Kevin A. Becker and David L. Nichols
observed increases in cardiometabolic responses ( Protas, Stanley, Jankovic, & MacNeill, 1996 ; Stanley, Protas, & Jankovic, 1999 ). To improve cardiorespiratory fitness and gait dysfunction, aerobic exercise on a motorized treadmill has been shown to be an effective intervention in those diagnosed with
Tatiane Piucco, Rogério Soares, Fernando Diefenthaeler, Guillaume Y. Millet and Juan M. Murias
physiological evaluations of skating on instrumented motorized treadmills. 5 , 6 However, even though these evaluations mimic physiological responses to skating, the access to this type of equipment is limited and expensive. As an alternative and an inexpensive method that simulates speed skating conditions
Tatiane Piucco, Fernando Diefenthaeler, Rogério Soares, Juan M. Murias and Guillaume Y. Millet
with a lower V ˙ O 2 max and higher maximal heart rate (HR max ) during skating when compared with running or cycling. 4 – 6 Despite the lack of specificity, cycle ergometer or treadmill running tests are widely used in speed skating 7 for monitoring physiological changes and establishing training
Ian Rollo and Clyde Williams
The aim of this study was to investigate the influence of ingesting a carbohydrate-electrolyte solution (CHO-E) on performance during a 1-hr treadmill run. Eight male endurance-trained runners (age 31 ± 8 yr, M ± SD) completed three 1-hr performance runs separated by 1 wk. The study used a double-blind placebo (PLA) controlled design. On 2 occasions (P1, P2) runners consumed a placebo solution, 8 ml/kg body mass (BM), 30 min before and 2 ml/kg BM at 15-min intervals throughout the 1-hr run. On a separate occasion they consumed the same quantity of a 6.4% CHO-E solution (C). Total distances covered for P1, P2, and C trials were 13,685 ± 1,116 m, 13,715 ± 1,143 m, and 14,046 ± 1,104 m, respectively. Although there was no difference between the 2 PLA trials (p > .05), the distance covered during the C trial was significantly greater than in either PLA trial (p < .05). CHO ingestion resulted in a higher blood glucose concentration only at the onset of exercise (p < .05) compared with the PLA trials. Blood lactate, respiratory-exchange ratio, and CHO oxidation were similar in all 3 trials. In conclusion, ingestion of a 6.4% CHO-E solution before and during exercise was associated with improved running performance in runners compared with the ingestion of a color- and taste-matched placebo.
James S. Hogg, James G. Hopker and Alexis R. Mauger
The novel self-paced maximal-oxygen-uptake (VO2max) test (SPV) may be a more suitable alternative to traditional maximal tests for elite athletes due to the ability to self-regulate pace. This study aimed to examine whether the SPV can be administered on a motorized treadmill.
Fourteen highly trained male distance runners performed a standard graded exercise test (GXT), an incline-based SPV (SPVincline), and a speed-based SPV (SPVspeed). The GXT included a plateau-verification stage. Both SPV protocols included 5 × 2-min stages (and a plateau-verification stage) and allowed for self-pacing based on fixed increments of rating of perceived exertion: 11, 13, 15, 17, and 20. The participants varied their speed and incline on the treadmill by moving between different marked zones in which the tester would then adjust the intensity.
There was no significant difference (P = .319, ES = 0.21) in the VO2max achieved in the SPVspeed (67.6 ± 3.6 mL · kg−1 · min−1, 95%CI = 65.6–69.7 mL · kg−1 · min−1) compared with that achieved in the GXT (68.6 ± 6.0 mL · kg−1 · min−1, 95%CI = 65.1–72.1 mL · kg−1 · min−1). Participants achieved a significantly higher VO2max in the SPVincline (70.6 ± 4.3 mL · kg−1 · min−1, 95%CI = 68.1–73.0 mL · kg−1 · min−1) than in either the GXT (P = .027, ES = 0.39) or SPVspeed (P = .001, ES = 0.76).
The SPVspeed protocol produces VO2max values similar to those obtained in the GXT and may represent a more appropriate and athlete-friendly test that is more oriented toward the variable speed found in competitive sport.
Olivier Girard, Franck Brocherie, Jean-Benoit Morin and Grégoire P. Millet
To determine the intrasession and intersession (ie, within- and between-days) reliability in treadmill sprinting-performance outcomes and associated running mechanics.
After familiarization, 13 male recreational sportsmen (team- and racket-sport background) performed three 5-s sprints on an instrumented treadmill with 2 min recovery on 3 different days, 5–7 d apart. Intrasession (comparison of the 3 sprints of the first session) and intersession (comparison of the average of the 3 sprints across days) reliability of performance, kinetics, kinematics, and spring-mass variables were assessed by intraclass correlation coefficient (ICC) and coefficients of variation (CV%).
Intrasession reliability was high (ICC > .94 and CV < 8%). Intersession reliability was good for performance indices (.83 < ICC < .89 and CV < 10%, yet with larger variability for mean velocity than for distance covered or propulsive power) and kinetic parameters (ICC > .94 and CV < 5%, yet with larger variability for mean horizontal forces than for mean vertical forces) and ranged from good to high for all kinematic (.88 < ICC < .95 and CV ≤ 3.5%) and spring-mass variables (.86 < ICC < .99 and CV ≤ 6.5%). Compared with intrasession, minimal detectable differences were on average twice larger for intersession designs, except for sprint kinetics.
Instrumented treadmill sprint offers a reliable method of assessing running mechanics during single sprints either within the same session or between days.
Kenneth H. Pitetti, Bart Jongmans and Bo Fernhall
The purpose of this study was to examine the validity and reliability of a treadmill (TM) test for adolescents with multiple disabilities, as defined by PL 105-17. Participants were 16 males and 2 females, ages 11 to 21 (M 14.9 ± 3.2), identified by teachers as potentially able to perform a TM test. Data were collected two times, separated by 2 to 3 weeks. Of the 18 adolescents, 5 could not perform the protocol, and 4 could not complete the test. Intraclass (test–retest) reliability coefficients for HRpeak, V̇Epeak, RERpeak, and V̇O2peak were .90, .90, .88, and .77, respectively, for the remaining 9 participants. Although none of these participants were able to meet the criteria commonly associated for a valid TM maximaltest (V̇O2max), they did meet the criteria for a valid TM maximum test (V̇O2peak) (Wasserman, Hansen, Sue, Whipp, & Casaburi, 1994). Further study of the feasibility of treadmill testing for this population is recommended.
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.
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.