PubMed Health⌕ Search

Biomedical subjects

P J Van Handel

Publications and source records attributed to P J Van Handel.

11 recordsLinked to original sources
PubMed1991

The preparticipation fitness test.

A fitness evaluation for training prescription may include a number of types of tests. Most common is the measurement of maximal aerobic capacity, because it requires optimal functioning of the cardiovascular, respiratory, and neuromuscular systems. Age, health status, and prior activity level, in part, dictate what type of protocol is used for the evaluation. Regardless of the protocol, it is useful to obtain quantitative measures of both submaximal response and maximal capacity for the training prescription. This is especially true for athletes who are attempting to induce very specific physiologic adaptations.

Exercise Test↗
PubMed1989

Development of valid pulmonary function equations for trained athletes.

The validity of commonly recommended pulmonary function prediction equations (Bulletin Européen de Physiopathologie Respiratoire, Clinical Respiratory Physiology) was tested with two samples (n1 = 156; n2 = 218) of well-trained athletes. Pulmonary function measures (FVC, TLC, RV, FEF25%-75%, FEV1.0, PEF, RV/TCL ratio, FEV1.0/FVC ratio) were typically very reliable but inaccurately predicted with recommended equations based upon anthropometric characteristics. Newly developed "unisex" regression equations were developed with "dummy" coding of gender (i.e., 0 = female; 1 = male), age, height, weight, and various interactions. The new equations were validated with a subsample of group one, cross-validated with the remaining portion of group one, and then cross-validated again with the 218 subjects from sample two. The newly created pulmonary function prediction equations are more valid for well-trained athletes than the equations in use for the general population.

Adult↗
PubMed1983

Sports physiology: testing the athlete.

The Sports Physiology Laboratory at the Olympic Training Center has essentially three responsibilities. (1) education of the athlete and coach, (2) service to National Governing Bodies that request, on behalf of their substructure, testing or educational programs, and (3) research on specific questions of interest to an athletic group.

Biomechanical Phenomena↗
PubMed1982

Muscle glycogen storage and its relationship with water.

This study examined the relationship between muscle glycogen and muscle water content. Exercise dietary manipulations were used to vary skeletal muscle glycogen levels in four groups of rodents: (1) eight animals were sedentary controls (SC); (2) ten animals were treadmill familiarized and allowed to recover 24 h before sacrifice (F); (3) ten animals were treadmill familiarized and exercised to exhaustion (E); (4) ten animals were treadmill familiarized, exercised to exhaustion, and allowed to recover with food and water ad libitum for 72 h (ER). All animals were sacrificed in a resting state to normalize intracellular, extracellular, and interstitial water compartments; thus, the E group was sacrificed 45 m in following their run. The treatments altered skeletal muscle glycogen to values ranging from 10.0 to 30.2 mumol glucosyl units/g wet tissue weight. Neither muscle triglyceride nor protein levels were affected by the treatments. Muscle water content expressed as mumol H2O lost/g wet tissue weight or made relative to protein content showed no consistent relationship to the glycogen content. These data, therefore, do not support the commonly accepted muscle glycogen-to-water ratio of 1.0:2.7 (g:g). Further work is necessary to quantify the exact amount of water that is actually associated with the glycogen complex.

Animals↗
PubMed1981

Effects of treadmill running on oxidative capacity of regenerated skeletal muscle.

The purpose of the present study was to examine the effects of treadmill running on the oxidative capacity of regenerated rodent skeletal muscle. The soleus, plantaris, and gastrocnemius muscles were removed under general anesthesia from one hindlimb of young female rats (N = 15). The visible "white" portion of the latter muscle was minced into 1 mm3 fragments and autotransplanted leaving both the tibial and sural nerves intact. Six animals were treadmill run daily beginning 4 days post-surgery. Intensity and duration were progressively increased such that by day 45 the animals were running 1 h at 21.5 m . min-1 up a 15% grade, The regenerated muscle homogenates had a significantly lower capacity for maximal pyruvate + malate oxidation and smaller mass relative to the contralateral gastrocnemius. The exercise program significantly increased these parameters, tending to normalize the values. Some factor associated with exercise stimulated recovery from the muscular trauma.

Animals↗
PubMed1981

Alteration in the lactate threshold with changes in substrate availability.

The lactate threshold (LT) was studied (N=9) during ergometer cycling under control (C), high blood glucose (G), and high blood free fatty acid (F) conditions. During the G trial blood lactate (HLa) was greater than C at all work loads (P less than 0.05) Adjusted blood HLa values (HLa - pre-exercise value = delta HLa), however, were essentially the same for the C and G trials. Determination of the LT disclosed that there was no difference between the two treatments (C = 53.9 +/- 2.6% VO2 max; G=52.7 +/- 3.1% VO2max). Elevation of blood FFA levels, however, reduced both the HLa and deltaHLa at all work loads from 150-250 W (P less than 0.05) although VO2 was the same as C. In addition, a significant increase in the LT (F = 59.8 +/- 2.6% VO2max) was found for the F treatment. These data suggest that (1) the LT can be altered by substrate availability and (2) that muscle tissue anoxia may not be solely responsible for lactate production during submaximal work.

Adult↗
PubMed1980

Muscle respiratory capacity and fiber type as determinants of the lactate threshold.

This study examined the relationship between the respiratory capacity of an individual's skeletal muscle and the work rate at which blood lactate accumulation begins (lactate threshold). Comparisons were also made among fiber type, VO2max, and the lactate threshold. Muscle biopsies were taken from the vastus lateralis muscle for determination of respiratory capacity and fiber type (myosin ATPase). The lactate threshold was assessed in terms of both the absolute work rate (VO2) and relative work rate (%VO2max). The capacity of muscle homogenates to oxidize pyruvate was significantly (P less than 0.01) related to the absolute (r = 0.94) and relative (r = 0.83) lactate thresholds. Significant positive correlations (P less than 0.01) were also found between the percent of slow-twitch fibers and absolute (r = 0.74) and relative (r = 0.70) lactate thresholds. The results suggest that the muscle's respiratory capacity is of primary importance in determining the work rate at which blood lactate accumulation begins. They also suggest that the proportion of slow-twitch fibers may play an important role in determining the relative lactate threshold.

Adult↗
PubMed1975

Leg muscle metabolism during exercise in the heat and cold.

In an effort to assess the effects of environmental heat stress on muscle metabolism during exercise, 6 men performed work in the heat (Tdb = 44 degrees C, RH = 15%) and cold (Tdb = 9 degrees C, RH = 55%). Exercise consisted of three 15-min cycling bouts at 70 to 85% VO2max, with 10-min rest between each. Muscle biopsies obtained from the vastus lateralis before and after each work bout were analyzed for glycogen and triglyceride content. Venous blood samples drawn before and after exercise were assayed for lactate, glucose, free fatty acids, hemoglobin, and hematocrit. Oxygen uptake, heart rates and rectal temperatures were all significantly higher during exercise in the heat. Blood lactate concentration was roughly twice as great during the heat experiments as that measured in the 9 degrees C environment. Muscle glycogen utilization per 60 min was significantly greater in the heat ( - 74 m moles/kg-wet muscle) as compared to the cold exercise (- 42 m moles/kg-wet muscle). On the average, muscle triglyceride declined 23% during exercise in the cold and 11% in the heat. The findings of an enhanced glycolysis during exercise in the heat is compatible with earlier studies which demonstrate a decreased availability of oxygen due to a reduction in muscle blood flow.

Adult↗