Joan Eckerson

Creighton University · Department of Exercise Science

This study investigated the effect of a commercially available ketone supplement on heart rate (HR), perceived exertion (RPE), blood lactate, glucose, and ketone concentrations, along with time to fatigue (TTF) during a running task to voluntary fatigue. Twelve NCAA Division I cross-country athletes took part in this randomized, double-blind, place...

Doxorubicin (DOX), a potent chemotherapy agent, useful in the treatment of solid tumors, lymphomas, and leukemias, is limited by its potentially lethal cardiotoxicity. However, exercise has been consistently shown to mitigate the side effects of DOX, including cardiotoxicity. To date, most studies examining the relationship between exercise and DOX...

This investigation aimed to determine the effect of a multi-ingredient pre-workout supplement (MIPS) on heart rate (HR), perceived exertion (RPE), lactate concentration, and time to fatigue (TTF) during a running task to volitional exhaustion. Eleven NCAA Division I cross-country runners (20 ± 2 year; height: 171 ± 14 cm; weight: 63.5 ± 9.1 kg) par...

Despite extensive research on creatine, evidence for use among females is understudied. Creatine characteristics vary between males and females, with females exhibiting 70–80% lower endogenous creatine stores compared to males. Understanding creatine metabolism pre- and post-menopause yields important implications for creatine supplementation for p...

The use of dietary supplements has become increasingly common over the past 20 years. Whereas supplements were formerly used mainly by elite athletes, age and fitness status no longer dictates who uses these substances. Indeed, many nutritional supplements are recommended by health care professionals to their patients. Creatine (CR) is a widely use...

Doxorubicin (DOX), an effective anticancer agent, can damage cardiac and skeletal muscle tissue via excessive generation of reactive oxygen species (ROS). Supplemental creatine (Cr) has been shown to have a therapeutic role in disease states characterized by increased oxidative stress. To investigate the effects of Cr and creatinine (CrN) on DOX-in...

Previous research has shown that resistance training (RT) prior to doxorubicin (DOX) treatment attenuates the decline in muscle dysfunction; however, the effect of RT during DOX treatment is less known. Purpose Investigate the effects of RT prior to and during a 4 wk course of incremental DOX treatment on skeletal muscle function. Methods Male,...

CREATINE (CR) IS AN EFFECTIVE ERGOGENIC AID FOR FEMALE ATHLETES, BUT MAY BE OVERLOOKED BECAUSE OF A PERCEPTION THAT IT CAUSES WEIGHT GAIN. STUDIES USING WOMEN SHOW THAT BOTH SHORT-TERM AND LONG-TERM CR SUPPLEMENTATION ENHANCES MUSCULAR STRENGTH AND POWER AND OTHER MEASURES OF ANAEROBIC AND AEROBIC EXERCISE PERFORMANCE WITH MINIMAL EFFECTS ON BODY C...

Although protein is not a shortfall nutrient for most young adults, some groups, such as young women, are more at risk for generally nutrient‐poor diets, and may benefit from increased protein intake. Consuming a high protein breakfast (BF) has been shown to have favorable effects on satiety and subsequent energy intake. To further explore the effe...

Creatine is widely used by both elite and recreational athletes as an ergogenic aid to enhance anaerobic exercise performance. Older individuals also use creatine to prevent sarcopenia and, accordingly, may have therapeutic benefits for muscle wasting diseases. Although the effect of creatine on the musculoskeletal system has been extensively studi...

Obesity has reached what may be considered epidemic proportions in the United States, not only for adults but for children. Because of the medical implications and health care costs associated with obesity, as well as the negative social and psychological impacts, many individuals turn to nonprescription nutritional weight loss supplements hoping f...

Consumption of energy drinks by both recreational and competitive athletes has increased dramatically in recent years. The primary ingredients in many energy drinks include caffeine (CAF) in various forms and taurine. The purpose of this randomized, doubleblind, crossover study was to examine the effect of sugar-free (SF) Red Bull (RB) containing C...

Consumption of energy drinks by both recreational and competitive athletes has increased dramatically in recent years. The primary ingredients in many energy drinks include caffeine (CAF) in various forms, as well as taurine. The purpose of this randomized, double-blind, crossover study was to examine the effect of sugar-free (SF) Red Bull (RB) con...

A variety of methods exist to measure ankle dorsiflexion range of motion (ROM). Few studies have examined the reliability of a novice rater. The purpose of this study was to determine the reliability of ankle ROM measurements using three different techniques in a novice rater. Twenty healthy subjects (mean±SD, age=24±3 years, height=173.2±8.1 cm, m...

The idiopathic inflammatory myopathies (IIM) are a group of immune-mediated disorders characterized by progressive muscle weakness and inflammatory infiltrates (T-cells and macrophages) within the skeletal muscle. They also may occur in association with a systemic connective tissue disease or other .... .

Myalgia is a general term used to describe diffuse muscular ....

Numerous reports exist concerning relationships between muscle fiber types or myosin heavy chain expression and in vivo human muscle performance. Whereas in vitro high power performances in single muscle cells are most associated with type IIB/X fibers expressing primarily MHC IIb/x, these relationships are not always observed for in vivo volitiona...

The purpose of the present study was to determine the validity of various laboratory methods for estimating percent body fat (%fat) in NCAA Division I college female athletes (n = 29; 20 +/- 1 year). Body composition was assessed via hydrostatic weighing (HW), air displacement plethysmography (ADP), and dual-energy X-ray absorptiometry (DXA), and e...

This study assessed tolerance to fluid ingestion with repeated sessions of drinking while running. Runners (n = 7; age 22 +/- 2 yr; V O (2max) = 54.4 +/- 7.1 ml/kg/min) performed six 90-min runs (65 % V O (2max); separated by 7 - 11 days). During run 1, subjects drank a glucose-electrolyte solution AD LIBITUM for 1 min every 10 min. During runs 2 -...

The purpose of this study was to determine the effect of 30 days of single-dose creatine supplementation with phosphate salts (CPS) on body weight (BW) and anaerobic working capacity (AWC) in men. Using a double-blind design, 32 men randomly received 1 serving of either CPS (5 g Cr + 4 g phosphate) (n = 17) or 20 g of dextrose as placebo (PL) (n =...

The purpose of this study was to determine gastrointestinal (GI) permeability during prolonged treadmill running (60 min at 70 % V.O2max) with and without fluid intake (3 ml/kg body mass/10 min). Twenty runners (11 males, 9 females; age = 22 +/- 3 (SD) yrs; mean V.O2max = 55.7 +/- 5.0 ml/kg/min) completed four experiments: 1) rest, 2) running with...

This study assessed tolerance to fluid ingestion with repeated sessions of drinking while running. Seven trained distance runners (age 22 ± 2 yr; VO 2 max = 54.4 ± 7.1 ml/kg/min) performed six 90 min treadmill runs (~1/week) at 65% VO 2 max while ingesting a glucose‐electrolyte solution. During run 1 , subjects drank ad libitum every 10 min and swe...

Obesity has reached what may be considered epidemic proportions in the United States, not only for adults but for children. Because of the medical implications and health care costs associated with obesity, as well as the negative social and psychological impacts, many individuals turn to nonprescription nutritional weight loss supplements hoping f...

The effect of oral creatine (Cr) supplementation on performance has received a considerable amount of attention in recent years, and has been shown to be effective for enhancing both aerobic and anaerobic exercise performance. The majority of Cr research has used men as subjects; therefore, findings reported for men may not necessarily be generaliz...

The purpose of this study was to determine the effects of 2 and 6 days of creatine phosphate loading on anaerobic working capacity (AWC) and body weight (BW) in men and women. Sixty-one men (n = 31) and women (n = 30) randomly received 1 of 3 treatments (4 x 5 g.d(-1) x 6 days) using a double blind design: (a) 18 g dextrose as placebo (PL); (b) 5.0...

The purpose of this investigation was to determine the accuracy of near-infrared interactance (NIR) instruments and population-specific NIR equations for estimating percent body fat (% fat) in young wrestlers. Forty-four white male youth wrestlers (mean age +/- SD = 11.0 +/- 2.1 years) volunteered for this study. Thirteen NIR % fat estimates were c...

The purpose of this study was to determine the effects of 2 and 5 days of Cr loading on anaerobic working capacity (AWC) using the critical power (CP) test in women. Ten physically active women randomly received 2 treatments separated by a 5 week washout period: (A) 18 g dextrose as placebo (PL) or (B) 5.0 g Cr + 18 g dextrose taken 4 times per day...

This investigation tested predictions of specificity and guidance hypotheses by manipulating relative frequency of knowledge of results scheduling using a shuffleboard task. Participants were assigned to either a 100%-KR, three 50%-KR conditions (Constant, Fade, Reverse), or 00%-KR condition. Based on predictions of the specificity hypothesis, it w...

The purpose of this case study was to determine the effects of 15 wk of resistance exercise and creatine (Cr) supplementation on body composition, training volume, peak strength, and complete blood chemistry in a patient with myasthenia gravis (MG). The patient was a 26-yr-old man who was taking prednisone and azathioprine for his condition. The pa...

The purpose of this study was to examine the effects of fluid replacement on power output (PO), rating of perceived exertion (RPE), heart rate (HR), body weight (BW), urine osmolarity (Uosm), and urine electrolyte concentrations ([UNa+], [UK+], [UCl-]) in physically active men (n = 4) and women (n = 7). The participants were asked to generate their...

The purposes of this investigation were to (a) modify the y-intercepts of previously published skinfold (SF) equations using the constant error (CE) values from Stout et al. (24); (b) cross-validate the modified equations to determine their accuracy for estimating body density (BD) in young wrestlers; (c) derive a new SF equation for estimating BD...

The critical power (CP) cycle ergometer test, theoretically, provides an estimate of a power output that can be maintained without fatigue. It has been suggested that pyruvate (PYR) supplementation may enhance endurance capacity. Therefore, the purpose of this study was to examine the effect of PYR supplementation on CP. Using a double-blind random...

The purpose of this investigation was to determine the effect of creatine (Cr) loading on the onset of neuromuscular fatigue by monitoring electromyographic fatigue curves from the vastus lateralis muscle using the physical working capacity at the fatigue threshold (PWC(FT)) test. Using a double-blind random design, 15 women athletes [mean age 19.0...

Anaerobic working capacity (AWC) estimated from the critical power test provides a theoretically and experimentally valid estimate of work capacity associated with muscle energy reserves adenosine triphosphate and phosphocreatine. Creatine monohydrate (CM) supplementation has been shown to increase phosphocreatine stores in skeletal muscle and, in...

The purpose of this study was to examine the changes in bench press strength (BPS), vertical jump (VJ), 100 yd dash time, and fat-free weight (FFW) in football players following 8 weeks of supplementation with a carbohydrate placebo (CHO), creatine monohydrate (CM), or CM plus CHO. Using a double blind random design, 24 college football players wer...

This study examined the validity of the Accu-Measure(TM) (AM) and the Futrex 1000 (F-1000) for estimating % body fat (BF) by comparing the estimates to values obtained from skinfold equations (Sum3). Thirty Caucasian men (age 23 +/- 3 yrs) and 26 Caucasian women (21 +/- 2 yrs) participated in the study. Subjects practiced, then determined their %BF...

This investigation examined the effect of manipulating different quantities of variable practice in the acquisition phase on the retention and transfer performance of a dart throw. Participants in the Specific condition practiced a total of 75 acquisition trials from a distance of 2.39 m. Participants in the Specific + Variable condition practiced...

The present study examined the validity of bioelectrical impedence (BIA) equations for estimating fat-free weight (FFW) in female gymnasts by comparing the values to those obtained from underwater weighing (UWW). Ninety-seven female Caucasian high school gymnasts (mean age +/- SD = 15.7 +/- 1.1 yr) participated in the study. FFW from UWW was calcul...

This study examined the validity of bioelectrical impedance (BIA) equations for estimating fat-free mass (FFM) in 117 Caucasian athletes (M age ± SD = 11 ± 2 yrs) who volunteered to undergo underwater weighing (UWW) and BIA assessment. Eleven BIA equations and a machine-generated value (BIAM) were cross-validated. Cross-validation analyses included...

A preseason estimation of body composition may be useful for assigning a safe minimal body weight for female gymnasts. The present investigation examined the validity of 11 skinfold equations for predicting percent body fat (%fat) in high school female gymnasts (X age +/- SD = 15.7 +/- 1.2 yr) by comparing the values with those obtained from underw...

The purpose of this study was to examine the covariate influence of fat-free weight (FFW) on age-related increases in isokinetic peak torque for leg flexion and extension in high school female gymnasts. Seventy-two gymnasts (X age +/- SD = 15 7 +/- 1.2 yr) volunteered to be measured for isokinetic leg flexion and extension strength using a calibrat...

The purpose of the present study was to examine age-related changes in isokinetic leg flexion and extension peak torque (PT), PT/body weight (PT/ BW), and PT/fat-free weight (PT/FFW) in young wrestlers. Male wrestlers (N = 108; age M ± SD = 11.3 ± 1.5 years) volunteered to be measured for peak torque at 30, 180, and 300° · s-1. In addition, underwa...

The purpose of this study was to examine the covariate influence of fat-free weight (FFW) on agerelated increases in isokinetic peak torque for leg flexion and extension in high school female gymnasts. Seventy-two gymnasts([horizontal bar over]X age ± SD = 15.7 ± 1.2 yr) volunteered to be measured for isokinetic leg flexion and extension strength u...

The present study examined the validity of selected bioelectrical impedance (BIA) equations for estimating percent fat (% fat) in males and compared their validity with that of a commonly used skinfold equation (Sum3). One-hundred twenty-two Caucasian males (X +/- SD = 12.5 +/- 5.8% fat, as determined by underwater weighing) served as subjects. Sel...

This investigation examined the validity of skinfold (Sum 7 and Sum3), near-infrared interactance (NIR), and bioelectrical impedance (BIA) estimations of percent body fat (% fat) in 41 nonathletic young women (mean age +/- SD = 20.1 +/- 2.3 yrs) by comparing the estimates to values obtained from underwater weighing (mean % fat = 18.9 +/- 4.4). The...

The purpose of the present study was to determine the validity of near-infrared interactance (NIR) estimates of percent body fat (% fat) using Futrex-5000, Futrex-5000A, and Futrex-1000 instruments in youth wrestlers (age, M ± SD = 11.4 ± 1.5 years) by comparing them to % fat values from underwater weighing. Fifty-eight members of youth wrestling c...

The present investigation examined the validity of 16 skinfold equations for predicting body density (BD) in youth wrestlers (mean age +/- SD = 11.0 +/- 1.3 yr) by comparing the values to those obtained from underwater weighing. Forty-eight members of youth wrestling clubs (mean BD +/- SD = 1.0634 +/- 0.0125 g.cm-3) volunteered to serve as subjects...

The purposes of this investigation were to: (a) examine the electromyographic (EMG) responses from the vastus lateralis during a continuous ride to exhaustion at the neuromuscular fatigue threshold (EMGFT) and (b) determine what percentage of the power output at VO2max the EMGFT represents. Fifteen adult males (mean +/- SD = 22 +/- 2 years) volunte...

This investigation examined the validity of skinfold (Sum7 and Sum3), near-infrared interactance (F5000 and F1000), and bioelectrical impedance (BIA) equations for estimating percent body fat (% fat) in 20 black male (age = 21.0 +/- 3.0 yrs) volunteers by comparing the estimates to values obtained from underwater weighing (% fat = 13.9 +/- 7.0). Th...

The present investigation examined the validity of selected skinfold (Sum3), near-infrared interactance (F5000 and F1000), and bioelectrical impedance (BIA) equations for estimating percent body fat (% fat) in young adult males (mean age +/- SD = 22 +/- 3 yr) by comparing the estimates with values obtained from underwater weighing. Fifty-seven Cauc...