James Laskin

Relationship Between Functional Classification Levels and Anaerobic Performance of Wheelchair Basketball Athletes

Abstract Wheelchair basketball athletes are classified using the International Wheelchair Basketball Federation (IWBF) functional classification system. The purpose of this study was to evaluate the relationship between upper extremity anaerobic performance (AnP) and all functional classification levels in wheelchair basketball. Ninety-seven male athletes from the Polish and Lithuanian national wheelchair basketball leagues took part in this study. The Wingate Anaerobic Test was used to assess four AnP indexes with an arm crank ergometer. The level of AnP in wheelchair basketball athletes depends to some degree on classification level. No significant differences were found for the AnP indexes across levels 1.0–2.5 and 3.0–4.5. However, the AnP level for those in classes 1.0–2.5 was significantly lower than those in classes 3.0–4.5. The findings from this study provided some evidence that the IWBF functional classification system should be reexamined and that a consolidation of the current eight levels might be in order.

Influences of ventilation on maximal isometric force of the finger flexors

Force production may be influenced by the phase of ventilation during which force is exerted. To examine the potential influences of ventilation on variability in maximal force measurements, we recorded peak isometric forces of the finger flexors during normal breathing, forced inspiration, forced expiration, and the Valsalva maneuver in 14 healthy adult subjects. The peak force increased significantly from forced inspiration to forced expiration (about 10%). Both forced expiration and inspiration resulted in increases in the flexor/extensor cocontraction ratio, whereas the Valsalva maneuver had no significant effects on maximal force or cocontraction ratio. Thus, this study clearly demonstrates the effects of ventilation on maximal finger force‐generating capability. Ventilation needs to be controlled for accurate assessments of maximal force. Muscle Nerve, 2006

Aerobic, Anaerobic, and Skill Performance with Regard to Classification in Wheelchair Rugby Athletes.

The purpose of the study was to examine the sport-specific performance of wheelchair rugby players with regard to their classification. A group of 30 male athletes from the Polish Wheelchair Rugby League participated in the study. The seven International Wheelchair Rugby Federation classes were collapsed into four groups. Standardized measures of aerobic, anaerobic, and skill performance were examined to identify performance differences among the four groups. Major findings were that most differences were between Group I players and all others and that anaerobic performance was the most sensitive to classification differences. Another important finding was that for all other groups, with one exception, adjacent groups did not differ in anaerobic, aerobic, and sport-specific skill performance. The results of this study demonstrate the need to investigate other performance measures that will help in evaluating the current wheelchair rugby classification system.

Using a treadmill for the 6-minute walk test: reliability and validity.

PURPOSE The 6-minute walk test (6MWT) is used to predict aerobic capacity, evaluate functional performance, and assess the risk of mortality and morbidity of several chronic conditions. The purpose of this study was to determine the validity and reliability of the 6MWT on a treadmill, thus increasing the clinical use of the 6MWT. PARTICIPANTS Participants comprised 20 able-bodied persons (9 men, 11 women, 29.5 ± 9.7 years, 1.73 ± 1.0 m, 72.76 ± 18.92 kg). All participants reported being nonsmokers and without any known cardiopulmonary, neurological, or orthopedic conditions. Methods Participants took part in 3 repeated treadmill 6MWTs (T6MWTs) and a graded cycle ergometer test to determine maximum oxygen consumption (&OV0622;O2max). Results No statistically significant differences were found between the 3 T6MWTs for distance, rating of perceived exertion, or heart rate (HR) (P = .17, .47, and .44, respectively) using both a repeated measures 1-way analysis of variance and an intraclass correlation coefficient (model 2, 1). The reliability was best between the second and third T6MWTs for distance and HR (0.88 and 0.86, respectively). A predictive equation from the stepwise linear multiple regression was used: &OV0622;O2max (L/min) = −1.732 + (weight [kg] × 0.049) + (distance [m] × 0.005) + (HR [beats/min] × [−0.015]), r2 = 0.869, SEE = 0.399. The Bland-Altman plot found 95% of the data points within the limits of agreement. Conclusions The T6MWT protocol was found to be reliable for measuring distance and HR. It can reasonably predict absolute &OV0622;O2max in a healthy adult population and should be validated in those with established chronic disease.

Construct validity of myotonometric measurements of muscle compliance as a measure of strength

Myotonometric measurement of muscle compliance represents new technology that quantifies muscle tone. Compliance change during muscle contraction might provide an indirect measure of strength. The purpose of this study was to determine relationships among myotonometric measurements of muscle compliance, surface electromyographic (sEMG) measurements of muscle activation and joint force production during voluntary isometric knee extensions. The level of relationship will contribute to the construct validity of use of muscle compliance as an indirect strength measurement. Thirteen male subjects, mean age 25 +/- 1.5 years, participated. Simultaneous recordings of myotonometric, sEMG of the rectus femoris and isometric knee extension force measurements were taken at rest, during maximal voluntary contraction (MVC), and during 33% and 66% MVC contractions. Relationships among the three measurement procedures were calculated using correlation and regression analyses. Myotonometric measures of muscle compliance, sEMG and force measurements were highly correlated. Myotonometric measurements were best represented by a curvilinear (quadratic) relationship to sEMG (r = 0.82, p < 0.001) and joint force (r = 0.83, p < 0.001). The present experiments establish the construct validity of myotonometric measurements of muscle compliance as an indirect means of quantifying muscle strength and activation levels. This method, therefore, offers a possible alternative for cases in which direct measurement of joint force or sEMG is difficult or inappropriate.

Comparison of lateral abdominal muscle thickness between weightlifters and matched controls

OBJECTIVEnTo compare lateral abdominal muscle thickness between weightlifters and matched controls.nnnDESIGNnA case control study design.nnnSETTINGnUniversity laboratory.nnnSUBJECTSn16 female Thai national weightlifters and 16 matched controls participated in this study.nnnMAIN OUTCOME MEASURESnUltrasound imaging with a 12-MHz linear array was used to measure the resting thickness of transversus abdominis (TrA), internal oblique (IO) and total thickness (Total) of lateral abdominal muscle (LAM) on the right side of abdominal wall. The absolute muscle thickness and the relative contribution of each muscle to the total thickness were determined.nnnRESULTSnWeightlifters had significantly thicker absolute TrA and IO muscles than matched controls (pxa0<xa00.01). Further, the relative thickness of the IO was significantly greater in weightlifters than matched controls (pxa0<xa00.05).nnnCONCLUSIONSnThe findings of this study suggest that routine Olympic style weight training among female weightlifters appears to result in preferential hypertrophy or adaptation of the IO muscle.

GENDER DIFFERENCES IN CARDIOVASCULAR RESPONSE TO ISOMETRIC EXERCISE IN THE SEATED AND SUPINE POSITIONS 999

ABSTRACT Donald R Melrose. Gender Differences In Cardiovascular Response To Isometric Exercise In The Seated And Supine Positions. JEP online . 2005;8(4):29-35. The purpose of this study was to 1) determine if the cardiovascular responses to isometric exercise differ between genders, and 2) determine if posture affects cardiovascular responses to isometric n women and 15 men (age 22.6±4.2 yrs) performed two randomized (seated or supine) maximal IHG trials at 40 %MVC one week apart. Blood pressure (BP) and heart rate (HR) measurements were collected at rest (RT), the first minute of exercise (M1), prior to failure (PF), and at 30 s of recovery following failure (RC). Mean arterial pressure (MAP), pulse pressure (PP), and rate pressure product (RPP) were calculated from BP and HR data. Analyses showed significant time by gender interactions for diastolic blood pressure (DBP) and MAP. Males had significantly higher DBP than females at M1 (105.46±14.97 vs. 92.59±13.14 mmHg), PF (122.46±11.23 vs. 109.50±13.72 mmHg) and RC (85.83±4.11 vs. 73.46 ± 8.35 mmHg) and higher MAP measurements than females at M1 (120.32 ± 13.76 vs. 105.43 ± 13.76 mmHg), PF (136.44 ± 8.65 vs. 24.31 ±13.34 mmHg), and RC (100.44 ±8.21 vs. 87.67 ±8.26 mmHg). DBP, MAP, and HR were significantly higher in the seated position than in the supine position for both genders. It was concluded that 1) men significantly increase MAP and DBP upon initiation of submaximal IHG exercise through recovery regardless of posture, 2) women have significantly lower blood pressure measurements than men during submaximal IHG exercise regardless of posture, and 3) posture has a significant affect on cardiovascular response during submaximal IHG exercise.

Consumption of star fruit juice on pro-inflammatory markers and walking distance in the community dwelling elderly

PURPOSEnThis study aimed to evaluate the effect of star fruit juice supplementation on tumor necrosis factor-alpha (TNF-α), interleukin-23 (IL-23) and interleukin-2 (IL-2), nitric oxide (NO), and 6 min walking distance (6MWD) in a group of elderly individuals.nnnMETHODSnTwenty-nine individuals (20 males, 9 females) with a mean age of 72.4±8.3 years completed this study. A two-week control period was followed by four weeks of 100g fresh star fruit juice consumption twice per day after meals.nnnRESULTSnPlasma TNF-α, IL-23, IL-2, NO and the 6MWD were evaluated twice during the control period (weeks 0 and 2) and once after the star fruit juice consumption (week 6).nnnRESULTSnThe results showed that all parameters in the blood did not change significantly during the control period. After 4 weeks of star fruit juice consumption, a significant reduction in NO, TNF-α and IL-23 was found; however, there was no change in IL-2. Moreover, the 6MWD increased significantly at week 6, when compared to that at week 0 and 2. Furthermore, the results also showed a significantly positive and negative correlation of NO and TNF-α to the 6MWD, but no correlation of IL-23 and IL-2.nnnCONCLUSIONnThis preliminary study concluded that consumption of star fruit juice at 100g twice daily for one month can significantly depress the pro-inflammation cytokines: TNF-α, IL-23, and NO, while increasing walking distance. Low TNF-α and high NO also present a significant correlation to walking capacity in elderly individuals.

A preliminary study on the effects of star fruit consumption on antioxidant and lipid status in elderly Thai individuals

Objective The aims of this preliminary study were to evaluate the antioxidant and lipid status before and after star fruit juice consumption in healthy elderly subjects, and the vitamins in star fruit extracts. Methods A preliminary designated protocol was performed in 27 elderly individuals with a mean (±SD) age of 69.5±5.3 years, by planning a 2-week control period before 4 weeks of consumption of star fruit twice daily. Oxidative stress parameters such as total antioxidant capacity, glutathione, malondialdehyde, protein hydroperoxide, multivitamins such as l-ascorbic acid (Vit C), retinoic acid (Vit A), and tocopherol (Vit E), and the lipid profile parameters such as cholesterol, triglyceride, high-density lipoprotein-cholesterol (HDL-C) and low-density lipoprotein-cholesterol (LDL-C) were analyzed. Moreover, Vit C, Vit A, and Vit E levels were evaluated in the star fruit extracts during the 4-week period. Results In the 2-week control period, all parameters showed no statistically significant difference; after 4 weeks of consumption, significant improvement in the antioxidant status was observed with increased total antioxidant capacity and reduced malondialdehyde and protein hydroperoxide levels, as well as significantly increased levels of Vit C and Vit A, when compared to the two-time evaluation during the baseline periods. However, glutathione and Vit E showed no statistical difference. In addition, the HDL-C level was higher and the LDL-C level was significantly lower when compared to both baseline periods. But the levels of triglyceride and cholesterol showed no difference. Vit C and Vit A were identified in small quantities in the star fruit extract. Conclusion This preliminary study suggested that consumption of star fruit juice twice daily for 1 month improved the elderly people’s antioxidant status and vitamins, as well as improved the lipoproteins related to Vit C and Vit A in the star fruit extract.

The effect of a needle biopsy of the vastus lateralis on isokinetic muscular performance.

Objective:To determine the acute effects of a needle muscle biopsy of the vastus lateralis on knee extension and flexion strength and endurance. Design:Pretest-posttest design. Testing order of right or left leg was randomly determined. Setting:Research Laboratory, University of Alberta, Edmonton Alberta, Canada. Participants:The subjects were 8 female and 11 male volunteers who were recreationally active. The mean age, height, and weight were 23 ± 5 years, 174.6 ± 9.2 cm, and 73.5 ± 7.3 kg, respectively. Intervention:Isokinetic testing for knee extension and flexion was performed on both legs before and after a biopsy of the right vastus lateralis muscle. Main Outcome Measures:Knee extension and flexion peak torque measured at an angular velocity of 1.05 rad.s-1. Mean torque during 25 consecutive maximal contractions at 3.14 rad.s-1 for knee extension and flexion exercise. Results:There was a significant decrease in right knee extension peak torque after the biopsy of the vastus lateralis muscle. No other differences were noted. Conclusions:These findings demonstrated an acute inhibition of knee extension peak torque but not endurance because of a muscle biopsy of the involved musculature.