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    Factors influencing the exertional heat stress response in athletic females : a thesis submitted in partial fulfilment of the requirements for the degree of Doctor of Philosophy, School of Sport, Exercise and Nutrition, Massey University, Palmerston North, New Zealand
    (Massey University, 2022) Zheng, Huixin
    Climate change continues to expose an increasing proportion of the global population to more frequent extreme heat events. Concurrently, our society has seen an increase in the number of women that participate in physically demanding leisure time (exercise and sport) and occupational activity. Yet, limited research has been conducted to understand the female physiological responses to exercise-heat stress, especially when considering their various ovarian hormone profiles. This thesis expands our understanding of the female physiological responses to heat stress from different perspectives. Firstly, previous evidence has demonstrated that ambient heat stress amplifies the increase in the cytokine interleukin-6 following exercise, an up-regulator of hepcidin - the hormone that downregulates iron metabolism. In Chapter Five iron sufficient females’ serum iron parameters and hepcidin levels following a self-paced cycling work trial were compared in temperate and hot conditions, and different menstrual phases. IL-6 and hepcidin both increased post-exercise (198% and 38%, respectively), interestingly, neither were affected by ambient temperature or menstrual phase (all p>0.15). Chapter Six determined the measurement error of a 30-min self-paced cycling protocol in moderate, warm-dry and warm-humid environments using thirty-three athletic women distinguished by their ovulatory status and ovarian hormone concentrations. With an ICC=0.90, p<0.01, and a mean CV of 4.7%, SEM of 3.8 kJ (2.1 W) and reliable bias of -2.1 kJ (-1.2 W), it was confirmed that this protocol has high test-retest reproducibility that is not influenced by ambient environment or a female’s hormonal/ovulatory status. Finally, in order to better predict females’ risk for exertional heat stress, Chapter Seven attempted to clarify the role of the ovarian hormones when explaining the variance of the core temperature response using the 30-min self-paced cycling protocol from Chapter Six in thirty-six trained women. It was found that estrogen contributes minimally, whilst baseline core temperature and power output contribute the most to peak core temperature during exercise. Taken together, this thesis deepens our understanding of females’ physiological responses and testing norms for current sport science practices. Specifically, it details iron metabolism responses when exposed to exercise-heat stress, elucidates the role of ovarian hormones regarding exertional heat strain and adds test-retest norms specific to athletic women to the available literature.
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    Athletes' experiences of being coached by their partner : a thesis presented in partial fulfilment of the degree of Master of Science in Health Psychology at Massey University, Auckland, New Zealand
    (Massey University, 2019) Burrows, Steffi J.
    The professional relationship between an athlete and coach is a unique relationship due to the large quantity and intensity of time spent together. When athletes engage in consensual relationships with their coach, the professional and personal spheres within this relationship interact together. Previous high-profile sporting examples within the media, highlight the unknown area of athletes being involved in both personal and professional relationships with their coach. Within the professional relationship, the coach is viewed to hold power compared to the athlete; therefore, previous literature links consensual sexual relationships between an athlete and coach with abuse literature. The aim of this recent study was to separate the coach-athlete personal and professional relationships from abusive literature within sporting literature. To help gain an enriched understanding of athletes’ experiences of being coached by their partner. Five female athletes, who were married to their coach, participated in an individual open-ended semi-structured interview. Their responses were analysed to explore their experiences of being coached by their partner, creating an enriched understanding of the interaction between the home and sporting domain. Thematic analysis indicated four themes within the data analysis: emotional connection, power dynamics within the interaction of the personal and professional domain, pragmatic issues within the interaction of the personal and professional relationship and having your coach with you at all times. Findings suggest that through the interaction of the personal and professional relationship, athletes’ experience an additional component of being emotionally connected to their coach. The power which coaches hold within the professional relationship is viewed by the athletes to be at a diluted level. Within the interaction of the personal and professional relationships blurred boundaries arise which creates pragmatic issues for the athlete. Lastly, athletes suggest positives that occur from having their coach with them at all times. The results of this study point to the positive aspects of the interaction of the personal and professional relationship, for athletes who are coached by their partner. Future research could include the perspective of coaches to understand their experiences. Additionally, future research could explore gender differences between athletes and coaches’ perspectives.
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    The last taboo in sport : menstruation in female adventure racers : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Psychology (Health Endorsement) at Massey University, Auckland, New Zealand
    (Massey University, 2016) Dykzeul, Amanda Jane
    Recent media attention has been drawn to the ‘last taboo in sport’, menstruation in the competitive female athlete. This thesis delves into the domain of sport to understand why this taboo exists and how menstruation is constructed in the gendered sport of Adventure Racing. With its traditionally patriarchal structure, the presence of women on the sportsground has long been resisted. Adventure racing is interesting because it requires a minimum of one woman in each team, and thus provides a unique context within which to study menstruation. The sporting literature has typically framed menstruation within a biomedical perspective, where sporting behaviour results in menstrual dysfunction and therefore as a threat not only to the athlete’s wider health, also her traditional role as child-bearer. The ability to construct menstruation as a positive experience has been limited, especially as the voice of female athletes themselves has been notably missing from the literature. Seven female adventure racers participated in this study to elucidate their experiences within training and competitive environments. Semi-structured interviews were held with each participant, and their dialogue interpreted thematically as to how they construct and manage menses within this context. The major themes drawn from the women’s voice include the woman as the compulsory piece of kit, as subordinate and weak, and as the caregiver. Despite the women’s right to compete, this equal opportunity did not transfer to their positioning within the team. Their perceived inferiority worked to keep menstruation hidden and bodies silenced in attempts to emulate the idealised masculine sporting body. In general, menstruation was constructed as a tolerated annoyance; it was to be dealt with by the individual akin to any other illness or injury that one of their male teammates might need to manage. In this way the women were able to compartmentalise their menses as an entity that could be controlled. It was constructed as ‘something’ that happened to their body, and thereby distanced themselves from the bodily process. Menstruation remained absent from talk, concealed in dialogue and action, and absence of menses was welcomed, its presence preferred once off the sportsground. The taboo status of menstruation remains firmly embedded in this gendered sporting domain.
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    The effects of a vitamin D randomised controlled trial on muscle strength and power in female adolescent athletes : a thesis presented in partial fulfillment of the requirements for the degree of Master of Science in Human Nutrition at Massey University, Albany, New Zealand
    (Massey University, 2013) Mitchell, Sarah
    Background: Vitamin D deficiency is widespread in the general public and emerging evidence has revealed it is common in athletic populations, particularly those who train indoors. Recent studies suggest that vitamin D deficiency is correlated with impaired skeletal muscle function; however there is limited evidence from randomised controlled trials that vitamin D supplementation can improve muscle strength and power in trained athletes. Objective: To investigate the effects of vitamin D3 supplementation on serum 25(OH)D concentrations and muscle strength and power in female adolescent athletes training predominantly indoors. Methods: Female adolescent dancers, gymnasts, and swimmers (n = 61) who trained regularly for at least five hours per week participated in this randomised double blind placebo controlled trial. Participants were stratified to receive 50,000 IU vitamin D3 or placebo every month for six months. Serum 25(OH)D concentrations, muscle strength (handgrip and isokinetic knee extensor and flexor torque), power (vertical jump), and anthropometric measurements were assessed at baseline and endpoint (n = 54). Results: At baseline, the median 25(OH)D concentration was 77.5 [63.5,92] nmol/L for the vitamin D group and 74 [64.5,88.5] nmol/L for the placebo group. Following six months of supplementation, serum 25(OH)D concentrations increased significantly in the vitamin D group (16.5 [7,46] nmol/L) (P = 0.001), but not the placebo group (-6.25 [-21,44] nmol/L). Peak torque (Nm) of the knee extensors in concentric and eccentric extension increased significantly for both groups (P <0.05), and there was no significant difference in change in peak torque between groups. After controlling for change in 25(OH)D and baseline 25(OH)D separately, supplementation with vitamin D was not associated with any of the strength or power variables. Conclusions: Supplementation of 50,000 IU of vitamin D3 per month improved vitamin D status but did not improve the chosen measures of muscle strength and power in this group of female adolescent athletes. This may be due in part to the small sample size and high baseline serum 25(OH)D concentrations seen in this cohort. Keywords: skeletal muscle strength, skeletal muscle power, athletes, dancers, gymnasts, vitamin D, 25(OH)D
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    Effect of caffeine supplementation on metabolism and physical and cognitive function in female intermittent games players : a thesis presented in partial fulfilment for the requirements of a Master of Science in Human Nutrition at Massey University, Auckland, New Zealand
    (Massey University, 2012) O'Donnell, Jemma May
    Purpose: To investigate the effects of caffeine ingestion on metabolism and physical and cognitive performance in female team-sport players taking a monophasic oral contraceptive. Method: In a randomized, double-blind, placebo-controlled crossover design, 10 participants (age 23.6 ± 4.1 y; height 1.62 ± 0.06 m; body mass 59.O2 max 50.0 ± 5.3 ml·kg-1·min-1) completed a 90 min intermittent treadmill-running protocol twice, during days 5-8 and 18-22 of their pill cycle. All participants were taking a monophasic oral contraceptive of the same hormonal composition (Levlen ED, Nordette, Monofeme, or Microgynon). During the familiarisation session participants completed a maximal oxygen uptake test, practiced the cognitive, strength, power testing, and underwent 30 min of the running protocol. Upon arrival at the laboratory for the main trials, hydration status was measured via urine specific gravity (USG) using a handheld refractometer and a heart rate (HR) monitor fitted. A capsule containing 6 mg∙kg-1 body mass (BM) of anhydrous caffeine or placebo (Maltodextrin, 1.62 kJ∙g-1) was administered 45 min before commencing exercise with a 500 ml bolus of water. Further 3 ml∙kg-1 BM boluses of water were provided every 15 min during exercise. Before, during and after the exercise protocol, venous blood samples were taken and cognitive (Choice Reaction Time, CRT; Digit Vigilance, DV; Stroop test), perceptual (Ratings of Perceived Exertion, RPE; Feeling Scale, FS; Felt Arousal Scale, FAS; Profile of Mood States, POMS), and physical tests (countermovement jump, CMJ; strength testing on the isokinetic dynamometer) were administered. These tests were then all performed again at a follow-up 12 h post session in the morning, including a venipuncture blood sample, and the addition of sleep quality assessment using the Leeds Sleep Evaluation Questionnaire (LSEQ). Results: There were no significant effects of caffeine supplementation on HR, USG, CMJ, isometric strength, RPE, cognitive performance or glucose and insulin concentrations. Caffeine supplementation improved levels of pleasure, activation and vigour compared to iv placebo, and reduced levels of fatigue (P < 0.05). Caffeine supplementation also improved average power in eccentric contractions of the knee extensors and flexors, and peak torque in the eccentric contractions of the knee flexors (P < 0.05). Getting to sleep and subsequent quality of sleep was impaired following caffeine supplementation (P < 0.05). Free fatty acid (FFA) concentration increased over the duration of exercise (P < 0.05), and increased at a greater rate on the caffeine trial (P < 0.05). Conclusions: This is the first controlled study to examine caffeine supplementation in female games players who are taking a low-dose monophasic oral contraceptive, using an intermittent based running protocol. These athletes experienced an improved performance in various strength and power aspects, but no improvement in cognitive performance. Perceptual and mood responses were also improved as a result of caffeine supplementation. Metabolically, caffeine had an effect on markers of fat metabolism but not on carbohydrate metabolism.
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    A measure of dietary protein requirement in endurance trained women : a thesis submitted in the partial fulfilment of the requirements for the degree of Master of Science in Sport and Exercise Science, Massey University, (Wellington, New Zealand)
    (Massey University, 2011) Houltham, Stuart Douglas
    Purpose: Inference from dietary surveys and experimental models suggest that the female endurance athlete dietary protein requirement is 15-20% less than their male counterparts, but to date empirical measurement of the habitual protein requirement has not been undertaken. Methods: 72-h nitrogen balance (NBAL) was determined in 10 female cyclists training 10.8 h·w-1 (SD: 2.82), following two habituated protein intakes: a) a diet representing normal habitual intake (NH) (Protein: 85g.d-1 Energy: 9078kJ·d-1), b) an isolcaloric high-protein diet (HP) (Protein: 166g·d-1, Energy: 8909kJ·d-1). Total 72-h nitrogen intake was determined from Leco total combustion analysis from samples of the ingested food items, while total loss was determined from micro-kjeldahl analysis of total 72-h urine, urea nitrogen concentration of regional resting and exercise sweat sampling, and literature-based estimates of fecal and miscellaneous nitrogen losses. Habituated protein requirement was estimated by the mean regression of the two estimates of 72-h nitrogen balance vs. nitrogen intake. Results: Mean (SD) 24-h dietary protein intake during the 72-h sampling period was NH: 85 (11g), HP: 166 (19g). Mean 24-h urinary nitrogen during the NH and HP blocks were 13.19 (2.39 g·d-1) and 21.53 (3.94 g·d-1) respectively. Sweat urea nitrogen excretion was NH: 0.33 (0.08 g·d-1) and HP: 0.54 (0.12 g·d-1). Normal habitual and high-protein intakes resulted in a mean negative and positive nitrogen balance, respectively (mean ± SD) (NH: -0.59 ± 1.64, HP: 2.69 ± 3.09). Estimated mean protein requirement to achieve NBAL was calculated to be 1.63 g·kg-1·d-1 (95% confidence interval: 1.14–3.77). Conclusions: Our data shows that the dietary protein requirement for well-trained females taking part in daily moderate intensity and duration endurance training is within the range of measured requirement for similarly trained men and suggests that the current estimated range of protein requirement for females may be inadequate.
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    Effect of moderate alcohol consumption on recovery from eccentric exercise induced muscle damage in females : a thesis presented in partial fulfilment of the requirements for the degree of in at Massey University
    (Massey University, 2011) McLeay, Yanita
    Introduction: Unaccustomed eccentric contractions produce micro-structural damage to skeletal muscle, initiating a chain of events involving inflammation, pain, and impaired muscle performance. These effects are felt most between 24-72 hours post exercise, but can last anywhere from a few days up to a week. Sports involving a large eccentric component include those that are running-based; with resulting damage often impacting on successive games (common during competition), or on ability to train. Binge-drinking post-games is a common activity seen amongst athletes; particularly those involved in team sports. Both acute and chronic alcohol consumption have known negative impacts on the brain and body organs and being classified as a drug, has associated regulations and restrictions. Athletes require fast recovery from exercise-induced muscle damage for optimal performance in subsequent games or training. The effect of alcohol, exercise, and/or the combination of the two may have a negative effect on muscle recovery post-game following an acute intake of alcohol. While these types of studies have been carried out on males, as of yet no such study has been done on females. Due to physiological differences, there may be variation in muscle response to alcohol compared to that of males. Thus the purpose of this study was to compare the effects of alcohol consumption post exercise-induced muscle damage, with that of an iso-caloric placebo on muscle recovery in females. Methods: Eight females (mean age 23 years; 65.2 ± 15kg; 164 ± 5.5cm) participated in a controlled, randomized, cross-over design study. Following a prescribed standardised meal, they carried out a damage protocol in which 300 maximal eccentric contractions of the quadriceps femoris muscle were performed on an isokinetic dynamometer. Post-exercise, an alcoholic beverage or a placebo was consumed. Treatment type and leg of damage were randomly assigned as evenly as possible, with the two trials being separated by a month. Measures of maximal isokinetic (concentric and eccentric) torque and isometric tension produced across the knee were measured in both the exercised and control leg pre-exercise, 36 hours (h) and 60h post-exercise. Creatine kinase activity and muscle soreness ratings (squat and step) were taken prior to damage and post-exercise up to 60h. Results: A moderate amount of alcohol consumption following eccentric exercise, significantly reduced isometric, concentric and eccentric peak and average peak torque 36h and 60h post-exercise (all p < 0.05). Significance differences in force output between time points were seen only in peak and average concentric torque. All three contraction types showed a significant time * treatment interaction effect (p < 0.05). Creatine kinase and ratings of perceived muscle soreness did not significantly differ between treatments. Conclusions: Our results suggest that similar to males, the consumption of alcohol following eccentric exercise-induced muscle damage elicits a greater reduction in muscle performance in the days following damage in females.