Effect of downhill running on motoneuron pool excitability

1992 ◽  
Vol 73 (3) ◽  
pp. 968-973 ◽  
Author(s):  
R. Bulbulian ◽  
D. K. Bowles
Keyword(s):  
Repeated Measures ◽  
M Wave ◽  
Running Exercise ◽  
Motoneuron Pool ◽  
Downhill Running ◽  
Treatment Conditions ◽  
Hoffman Reflex ◽  
Muscle Action Potential ◽  
Male Subjects ◽  
Level Running

The purpose of this study was to compare alterations in motoneuron pool excitability after eccentric-biased (ECC-B) downhill running exercise with non-biased (NO-B) level running exercise. Six male subjects (25–34 yr) participated in the study, which included ECC-B exercise (-10% grade) and NO-B exercise (0% grade) at 50% of maximal O2 uptake for 20 min. The control trial consisted of 20 min of quiet rest with all subjects participating in all conditions (repeated measures). Motoneuron pool excitability was measured by the Hoffman reflex (H-wave), which was expressed as a ratio (H/M ratio) of the maximal electrically stimulated muscle action potential (M-wave). NO-B exercise resulted in a 9.3 +/- 2.7% (SE) reduction in the H/M ratio. ECC-B exercise resulted in a 24.6 +/- 5.7% reduction in the ratio (P less than 0.05 for both). The two exercise treatment conditions were also significantly different from one another (P less than 0.05). Twenty-four-hour postexercise H/M ratios were similar to baseline (P greater than 0.05). Postexercise subjective muscle soreness assessment (DOMS) produced significant increases in DOMS of 36 and 166% immediately and 24 h after exercise, respectively, for the ECC-B trial only (P less than 0.001). The data show that ECC-B exercise results in greater postexercise H/M ratio reductions than NO-B exercise and that H/M ratio changes post-ECC-B exercise are not solely associated with DOMS.

Optimal Experimental Design With Nesting of Persons in Organizations

2013 ◽  
Vol 221 (3) ◽  
pp. 145-159 ◽  
Author(s):  
Gerard J. P. van Breukelen
Keyword(s):  
Repeated Measures ◽  
Optimal Number ◽  
Health Centers ◽  
Randomized Experiments ◽  
Optimal Sample ◽  
Treatment Conditions ◽  
Sampling Cost ◽  
Nested Designs ◽  
Simple Equations ◽  
Number Of Individuals

This paper introduces optimal design of randomized experiments where individuals are nested within organizations, such as schools, health centers, or companies. The focus is on nested designs with two levels (organization, individual) and two treatment conditions (treated, control), with treatment assignment to organizations, or to individuals within organizations. For each type of assignment, a multilevel model is first presented for the analysis of a quantitative dependent variable or outcome. Simple equations are then given for the optimal sample size per level (number of organizations, number of individuals) as a function of the sampling cost and outcome variance at each level, with realistic examples. Next, it is explained how the equations can be applied if the dependent variable is dichotomous, or if there are covariates in the model, or if the effects of two treatment factors are studied in a factorial nested design, or if the dependent variable is repeatedly measured. Designs with three levels of nesting and the optimal number of repeated measures are briefly discussed, and the paper ends with a short discussion of robust design.

Two-Year Repeated Study on Health Effect of Net-Step Exercise Program in Community-Dwelling Older Persons

2021 ◽  
Vol 7 (2) ◽  
Author(s):  
Mori M ◽  
◽  
Seko T ◽  
Ogawa S ◽  
Kitazawa K ◽  
...  
Keyword(s):  
Repeated Measures ◽  
Older Persons ◽  
Smoking Status ◽  
Health Effect ◽  
Exercise Program ◽  
Community Dwelling ◽  
Confounding Variables ◽  
One Year ◽  
Male Subjects ◽  
Female Subjects

Background: A light-burden and indoor physical exercise program called Net-Step Exercise (NSE) has been developed in Hokkaido, Japan. Conducting the two-year repeated survey with the Kihon Checklist (KCL) for the same older subjects living in a rural area of Hokkaido where a relatively large proportion of the older persons have participated in NSE activity, we assessed the effectiveness of NSE activity. Methods: The whole of 3,155 community-dwelling persons aged from 75 years to 79 years in 8 towns were the candidates of the study subjects, and 2,183 subjects (69.2%) responded to the first survey (2018 Survey), answering the questions about both frequency of participation in NSE and each item in KCL. The same survey (2019 Survey) was conducted one year later, and completed by 1,956 subjects (93.3%), excluding 25 dead persons or 60 persons who had moved away from the community during the year. In the 2018 Survey as well as the 2019 Survey, Adjusted Odds Ratio (AOR) and its 95% confidence interval (95%CI) of each sub-category of KCL for NSE Participants compared with NSE Non-participants was calculated with unconditional logistic regression by sex, adjusting for age, smoking status, and other potentially confounding variables. Repeated-measures Analysis of Variance (ANOVA) was also applied by sex. Results: Significantly reduced risk (AOR with 95% CI) was observed in NSE participants in difficulty in activities of daily living in the male subjects in the 2018 Survey (0.64, 0.42-0.98) and in the 2019 Survey (0.50, 0.32-0.79), as well as in the female subjects in the 2018 Survey (0.52, 0.38-0.70) and in the 2019 Survey (0.46, 0.33-0.65), houseboundness in the female subjects in the 2018 Survey (0.42, 0.29-0.60) and in the 2019 Survey (0.70, 0.51-0.96), impaired cognitive function in the male subjects in the 2018 Survey (0.58, 0.36-0.92), and depressive status in the female subjects in the 2018 Survey (0.66, 0.49-0.88). Significant findings were also shown in most of the above four sub-categories by analysis with repeated-measures ANOVA. Conclusion: Either performance of NSE itself or participation in the program, or both, may promote healthy status in the older persons.

Can Seventh Graders Learn Fractions from a Web-Based Pedagogical Agent? Using Comparison Groups Thre Times Over Several Weeks

2011 ◽  
pp. 334-348
Author(s):  
Shannon Adams ◽  
Bruce L. Mann ◽  
Henry Schulz
Keyword(s):  
Web Sites ◽  
Repeated Measures ◽  
Pedagogical Agents ◽  
Pedagogical Agent ◽  
Web Based ◽  
Educational Multimedia ◽  
Treatment Conditions ◽  
Post Test ◽  
Comparison Groups ◽  
Practice Questions

In this study, a Web-based pedagogical agent presented 7th grade students (n = 91) with examples and practice questions involving the multiplication and division of fractions. Pedagogical agents are animated, talking characters that can be made to introduce, guide or otherwise enhance educational Web sites. It was expected that school-age students using moving and talking pedagogical agents would retain more and find more creative solutions to problems than students in the other treatment conditions. A repeated measures-by-occasion research design was used to determine if the movement and or talking by the agent helped them learn to multiply and divide fractions. Results of the analyses showed that students learned from the pre-test to immediate post-test. But there were no effects for either modality (speech vs. text) or agent animation (movement vs. no movement). Consistent with a previous study with 7th grade students using educational multimedia (Mann, Newhouse, Pagram, Campbell, & Schulz, 2002) positive findings from using speech in educational multimedia may only be generalizable to adults and older adolescents. Implications are discussed regarding the instructional design of educational Web sites.

Importance of the Post-Knowledge Delay Interval on Transit Reaction

1983 ◽  
Vol 57 (1) ◽  
pp. 303-307 ◽  
Author(s):  
Reno J. Ramella ◽  
Robert L. Wiegand
Keyword(s):  
Delay Interval ◽  
Repeated Measures ◽  
Interval Data ◽  
Knowledge Of Results ◽  
Treatment Groups ◽  
Treatment Conditions ◽  
Response Interval ◽  
Temporal Location ◽  
Important Time ◽  
Variable Errors

The purpose of this study was to determine if transit reaction or anticipation of coincidence could be improved by allotting more processing time. 120 subjects were randomly assigned to one of six treatment groups. The groups were formed by changing the temporal location of knowledge of results within the research paradigm, specifically to control the possible confounding from the inter-response interval. Data were analyzed via a series of two 6 (treatment conditions) × 5 (trial blocks) factorial analyses of variance, with repeated measures on the last factor for absolute and variable errors. The post-knowledge delay interval was the most important time of the paradigm, and transit reaction was positively related to duration of processing.

Fatigability, relaxation properties, and electromyographic responses of the human paralyzed soleus muscle

1995 ◽  
Vol 73 (6) ◽  
pp. 2195-2206 ◽  
Author(s):  
R. K. Shields
Keyword(s):  
Soleus Muscle ◽  
Wave Amplitude ◽  
Close Association ◽  
Muscle Relaxation ◽  
Peak Torque ◽  
M Wave ◽  
Relaxation Properties ◽  
Fatigue Protocol ◽  
Acute Group ◽  
Muscle Action Potential

1. The goal of this study was to characterize the fatigability, contractile relaxation properties, electrophysiological responses, and histochemical properties of the human paralyzed soleus muscle to determine its relative plasticity. 2. Acute (< 6 wk, n = 3) and chronic (> 1 yr, n = 10) paralyzed individuals had the tibial nerve activated with a 20-Hz square wave delivered for 330 ms every second for 4 min. The soleus muscle peak torque, one-half relaxation time (1/2RT), normalized maximum rate of relaxation (nMRR), and mass muscle action-potential amplitude (M wave) were computed every 30 s. A soleus muscle biopsy was evaluated for myosin adenosine triphosphatase enzyme (ATPase; pH 9.4, 4.6, and 4.2) and nicotinamide adenine dinucleotide tetrazolium reductase (NADH-TR). 3. In the chronically paralyzed group the torque was significantly reduced within 30 s of the fatigue protocol. The 1/2RT and nMRR were also significantly changed within 30 s, supporting that muscle relaxation was prolonged. No significant changes were present at comparable times during the same 4-min fatigue protocol applied to the acutely paralyzed soleus muscle. M-wave amplitude was significantly reduced in the chronic group, but only at 3 min of the fatigue protocol. Conversely, no significant changes occurred to the M waves of the acute group. 4. The correlation was high between torque and nMRR (r = 0.88-0.97) and torque and 1/2RT (r = 0.88-0.96) for each chronic subject. A close association was also found between 1/2RT and nMRR (r = 0.88-0.92) for each chronic subject. Because these variables changed minimally in the acutely paralyzed group, a lower correlation was present (r = 0.45-0.52). 5. Torque was weakly correlated to M-wave amplitude (r = 0.55) for the chronically paralyzed group. The greatest change in torque occurred at a time (0-65 s) when the least amount of change occurred in the M-wave amplitude, suggesting that the source of fatigue was within the contractile mechanism and not attributable to neuromuscular transmission compromise. 6. Despite a close association between torque and relaxation properties during fatigue of the chronically paralyzed soleus muscle, there was a significant dissociation after 5 min of recovery. Torque recovered to 60%, whereas the relaxation properties were consistently fully recovered. This suggests that the mechanism causing torque reduction covaried with the mechanism leading to prolonged relaxation during fatigue, but during recovery the two mechanisms no longer covaried. M-wave amplitude was also completely recovered at 5 min despite continued torque depression.(ABSTRACT TRUNCATED AT 400 WORDS)

Improving Speed and Accuracy of Word Recognition in Reading Disabled Children: An Evaluation of Two Computer Program Variations

1988 ◽  
Vol 11 (4) ◽  
pp. 333-341 ◽  
Author(s):  
Andrew L. Cohen ◽  
Joseph K. Torgesen ◽  
Jeffrey L. Torgesen
Keyword(s):  
Computer Program ◽  
Repeated Measures ◽  
Word Reading ◽  
Relative Effectiveness ◽  
Disabled Children ◽  
Repeated Measures Design ◽  
Reading Vocabulary ◽  
Treatment Conditions ◽  
Speed And Accuracy ◽  
Reading Disabled

The present study investigated the relative effectiveness of two versions of a computer program designed to increase the sight-word reading vocabulary of reading disabled children. One version required children to type words into the computer as part of the practice activity; in the other no typing was involved. Subjects were nine reading disabled students, average age 10 years, 7 months. A repeated-measures design was used to expose all subjects three times to two treatment conditions and a no-practice control condition. Accuracy and speed of reading, as well as spelling accuracy for multisyllable words were measured in pre- and posttests. Both versions of the program proved to be equally effective in improving speed and accuracy of reading words, but the typing version was more effective in increasing spelling accuracy. However, students enjoyed the no-typing version better, and they were able to attain mastery levels for new words on this version faster than on the typing version. Implications of these results for reading software design are considered.

Effect of exercise intensity and duration on postexercise metabolism

1990 ◽  
Vol 68 (6) ◽  
pp. 2362-2368 ◽  
Author(s):  
C. J. Gore ◽  
R. T. Withers
Keyword(s):  
Body Fat ◽  
Exercise Intensity ◽  
Repeated Measures ◽  
O2 Consumption ◽  
Trained Subjects ◽  
Independent Variables ◽  
Repeated Measures Design ◽  
The Mean ◽  
Per Se ◽  
Male Subjects

Data are reported on the net recovery O2 consumption (VO2) for nine male subjects (mean age 21.9 yr, VO2max 63.0 ml.kg-1.min-1, body fat 10.6%) used in a 3 (independent variables: intensities of 30, 50, and 70% VO2max) x 3 (independent variables: durations of 20, 50, and 80 min) repeated measures design (P less than or equal to 0.05). The 8-h mean excess postexercise O2 consumptions (EPOCs) for the 20-, 50-, and 80-min bouts, respectively, were 1.01, 1.43, and 1.04 liters at 30% VO2max (6.8 km/h); 3.14, 5.19, and 6.10 liters at 50% VO2max (9.5 km/h); and 5.68, 10.04, and 14.59 liters at 70% VO2max (13.4 km/h). The mean net total O2 costs (NTOC = net exercise VO2 + EPOC) for the 20-, 50-, and 80-min bouts, respectively, were 20.48, 53.20, and 84.23 liters at 30% VO2max; 38.95, 100.46, and 160.59 liters at 50% VO2max; and 58.30, 147.48, and 237.17 liters at 70% VO2max. The nine EPOCs ranged only from 1.0 to 8.9% of the NTOC (mean 4.8%) of the exercise. These data, therefore, indicate that in well-trained subjects the 8-h EPOC per se comprises a very small percentage of the NTOC of exercise.

scholarly journals Level, Uphill, and Downhill Running Economy Values Are Correlated Except on Steep Slopes

2021 ◽  
Vol 12 ◽  
Author(s):  
Marcel Lemire ◽  
Mathieu Falbriard ◽  
Kamiar Aminian ◽  
Grégoire P. Millet ◽  
Frédéric Meyer
Keyword(s):  
Knee Extensor ◽  
Running Economy ◽  
Energy Costs ◽  
Strength Assessment ◽  
Cardiopulmonary Fitness ◽  
Downhill Running ◽  
Lower Limb Strength ◽  
Reaction Forces ◽  
Steep Slopes ◽  
Level Running

The aim of this study was first to determine if level, uphill, and downhill energy cost of running (ECR) values were correlated at different slopes and for different running speeds, and second, to determine the influence of lower limb strength on ECR. Twenty-nine healthy subjects completed a randomized series of 4-min running bouts on an instrumented treadmill to determine their cardiorespiratory and mechanical (i.e., ground reaction forces) responses at different constant speeds (8, 10, 12, and 14 km·h−1) and different slopes (−20, −10, −5, 0, +5, +10, +15, and +20%). The subjects also performed a knee extensor (KE) strength assessment. Oxygen and energy costs of running values were correlated between all slopes by pooling all running speeds (all r2 ≥ 0.27; p ≤ 0.021), except between the steepest uphill vs. level and the steepest downhill slope (i.e., +20% vs. 0% and −20% slopes; both p ≥ 0.214). When pooled across all running speeds, the ECR was inversely correlated with KE isometric maximal torque for the level and downhill running conditions (all r2 ≥ 0.24; p ≤ 0.049) except for the steepest downhill slope (−20%), but not for any uphill slopes. The optimal downhill grade (i.e., lowest oxygen cost) varied between running speeds and ranged from −14% and −20% (all p &lt; 0.001). The present results suggest that compared to level and shallow slopes, on steep slopes ~±20%, running energetics are determined by different factors (i.e., reduced bouncing mechanism, greater muscle strength for negative slopes, and cardiopulmonary fitness for positive slopes). On shallow negative slopes and during level running, ECR is related to KE strength.

scholarly journals Changes in Psychological and Cognitive Outcomes after Green versus Suburban Walking: A Pilot Crossover Study

2019 ◽  
Vol 16 (16) ◽  
pp. 2894 ◽  
Author(s):  
Junia N. de Brito ◽  
Zachary C. Pope ◽  
Nathan R. Mitchell ◽  
Ingrid E. Schneider ◽  
Jean M. Larson ◽  
...  
Keyword(s):  
Negative Affect ◽  
Positive Affect ◽  
Crossover Study ◽  
Repeated Measures ◽  
Digit Span ◽  
Cognitive Outcomes ◽  
Moderate Intensity ◽  
Directed Attention ◽  
Treatment Conditions ◽  
Middle Aged Adults

This study investigated the acute effects of repeated walking sessions within green and suburban environments on participants’ psychological (anxiety and mood) and cognitive (directed-attention) outcomes. Twenty-three middle-aged adults (19 female) participated in a non-randomized crossover study comprised of once-weekly 50-min moderate-intensity walking sessions. Participants walked for three weeks in each of two treatment conditions: green and suburban, separated by a two-week washout period. Eleven participants completed green walking first and 12 suburban walking first. For each walk, we used validated psychological questionnaires to measure pre- and post-walk scores for: (1) mood, evaluated via the Positive and Negative Affect Schedule (PANAS); (2) anxiety, assessed by the State-Trait Anxiety Inventory (STAI-S); and (3) directed-attention, measured using the visual Backwards Digit Span test (BDS). Repeated measures linear mixed models assessed pre- to post-walk changes within-treatment conditions and post-walk contrasts between-treatment conditions. Results indicated that anxiety decreased after green walking and increased after suburban walking (−1.8 vs. +1.1 units, respectively; p = 0.001). For mood, positive affect improved after green walking and decreased after suburban walking (+2.3 vs. −0.3 units, respectively; p = 0.004), and negative affect decreased after green walking and remained similar after suburban walking (−0.5 vs. 0 units, respectively; p = 0.06). Directed-attention did not improve from pre- to post-walk for either condition. Our results suggested that green walking may be more effective at reducing state anxiety and increasing positive affect compared to suburban walking.

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