9 results on '"Kirk, Christopher"'
Search Results
2. The Relationships Between External and Internal Training Loads in Mixed Martial Arts.
- Author
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Kirk, Christopher, Langan-Evans, Carl, Clark, David R., and Morton, James P.
- Subjects
ANALYSIS of variance ,PHYSICAL training & conditioning ,MARTIAL arts ,REGRESSION analysis ,EXERCISE intensity ,PROBABILITY theory - Abstract
Purpose: As a multidisciplined combat sport, relationships between external and internal training loads and intensities of mixed martial arts (MMA) have not been described. The aim of this study was to determine the external loads and intensities of MMA training categories and their relationship to internal loads and intensities. Methods: Twenty MMA athletes (age = 23.3 [5.3] y, mass = 72.1 [7.2] kg, stature = 171.5 [8.4] cm) were observed for 2 consecutive weeks. Internal load and intensity (session rating of perceived exertion [sRPE]) were calculated using the Foster RPE for the session overall (sRPE-training load [TL]) and segmented RPE (segRPE-TL) for each training category: warm-up, striking drills, wrestling drills, Brazilian jiujitsu (BJJ) drills, striking sparring, wrestling sparring, BJJ sparring, and MMA sparring. External load and intensity were measured via Catapult OptimEye S5 for the full duration of each session using accumulated Playerload (PLd
ACC ) and PLdACC per minute (PLdACC ·min−1 ). Differences in loads between categories and days were assessed via Bayesian analysis of variance (BF10 ≥ 3). Predictive relationships between internal and external variables were calculated using Bayesian regression. Results: Session overall sRPE-TL = 448.6 (191.1) arbitrary units (AU); PLdACC = 310.6 (112) AU. Category segRPE-TL range = 33.8 (22.6) AU (warm-up) to 122.8 (54.6) AU (BJJ drills). Category PLdACC range = 44 (36.3) AU (warm-up) to 125 (58.8) AU (MMA sparring). Neither sRPE-TL nor PLdACC changed between days. PLdACC was different between categories. Evidence for regressions was strong-decisive except for BJJ drills (BF10 = 7, moderate). R2 range =.50 to.77, except for warm-up (R2 =.17), BJJ drills (R2 =.27), BJJ sparring (R2 =.49), and session overall (R2 =.13). Conclusions: While MMA training categories may be differentiated in terms of external load, overall session external load does not change within or between weeks. Resultant regression equations may be used to appropriately plan MMA technical/tactical training loads. [ABSTRACT FROM AUTHOR]- Published
- 2024
- Full Text
- View/download PDF
3. Letter to the Editor From Kirk and Stebbings: “The Impact of Gender-affirming Hormone Therapy on Physical Performance”
- Author
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Kirk, Christopher, primary and Stebbings, Georgina K, additional
- Published
- 2024
- Full Text
- View/download PDF
4. The International Olympic Committee framework on fairness, inclusion and nondiscrimination on the basis of gender identity and sex variations does not protect fairness for female athletes
- Author
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Lundberg, Tommy R, Tucker, Ross, McGawley, Kerry, Williams, Alun G, Millet, Grégoire P, Sandbakk, Øyvind, Howatson, Glyn, Brown, Gregory A, Carlson, Lara A, Chantler, Sarah, Chen, Mark A, Heffernan, Shane M, Heron, Neil, Kirk, Christopher, Murphy, Marie H, Pollock, Noel, Pringle, Jamie, Richardson, Andrew, Santos-Concejero, Jordan, Stebbings, Georgina K, Christiansen, Ask Vest, Phillips, Stuart M, Devine, Cathy, Jones, Carwyn, Pike, Jon, Hilton, Emma N, Lundberg, Tommy R, Tucker, Ross, McGawley, Kerry, Williams, Alun G, Millet, Grégoire P, Sandbakk, Øyvind, Howatson, Glyn, Brown, Gregory A, Carlson, Lara A, Chantler, Sarah, Chen, Mark A, Heffernan, Shane M, Heron, Neil, Kirk, Christopher, Murphy, Marie H, Pollock, Noel, Pringle, Jamie, Richardson, Andrew, Santos-Concejero, Jordan, Stebbings, Georgina K, Christiansen, Ask Vest, Phillips, Stuart M, Devine, Cathy, Jones, Carwyn, Pike, Jon, and Hilton, Emma N
- Abstract
The International Olympic Committee (IOC) recently published a framework on fairness, inclusion, and nondiscrimination on the basis of gender identity and sex variations. Although we appreciate the IOC's recognition of the role of sports science and medicine in policy development, we disagree with the assertion that the IOC framework is consistent with existing scientific and medical evidence and question its recommendations for implementation. Testosterone exposure during male development results in physical differences between male and female bodies; this process underpins male athletic advantage in muscle mass, strength and power, and endurance and aerobic capacity. The IOC's “no presumption of advantage” principle disregards this reality. Studies show that transgender women (male-born individuals who identify as women) with suppressed testosterone retain muscle mass, strength, and other physical advantages compared to females; male performance advantage cannot be eliminated with testosterone suppression. The IOC's concept of “meaningful competition” is flawed because fairness of category does not hinge on closely matched performances. The female category ensures fair competition for female athletes by excluding male advantages. Case-by-case testing for transgender women may lead to stigmatization and cannot be robustly managed in practice. We argue that eligibility criteria for female competition must consider male development rather than relying on current testosterone levels. Female athletes should be recognized as the key stakeholders in the consultation and decision-making processes. We urge the IOC to reevaluate the recommendations of their Framework to include a comprehensive understanding of the biological advantages of male development to ensure fairness and safety in female sports.
- Published
- 2024
5. A 5-Year Analysis of Age, Stature and Armspan in Mixed Martial Arts.
- Author
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Kirk, Christopher
- Subjects
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MIXED martial arts , *STATURE , *OLDER athletes , *AGE , *COMBAT sports - Abstract
Purpose: Athlete stature and armspan is anecdotally assumed to provide an advantage in mixed martial arts (MMA), despite an absence of supporting data. In contrast, winners of MMA bouts have been shown to be younger than bouts losers. Whilst absolute measurements of stature, armspan and armspan:stature scale (A:S) have been shown to not distinguish between winners and losers of MMA bouts, relative differences between competitors have not been analysed. This study aimed to analyse 5 years of athlete age and morphological data to replicate and expand previous studies to determine whether absolute and/or relative age and morphological variables effect winning and losing in MMA. MethodsandResults: Bayes factor (BF>3) inferential analyses conducted on the cohort overall (n = 2,229 professional bouts), each year sampled and each individual body mass division found that only absolute (winners = 29.8 ± 4 years; losers = 30.7 ± 4.2 years) and relative age (winners = 0.82 ± 5.3 years younger than losers) differentiates between winners and losers across the whole cohort, in 4 of the 5 years, and in 4 of the 13 divisions sampled. Armspan appears to provide an advantage in heavyweight only (winners = 198.4 ± 6.6cm; losers = 196.1 ± 7.7cm), with greater A:S being a disadvantage (winners = 1.003 ± 0.022cm∙cm−1; losers = 1.010 ± 0.023 cm∙cm−1) in women's strawweight only. No variables had any effect on how bouts were won. Conclusions: These results confirm previous reports that the effect of athlete morphology is greatly overstated in MMA, appearing to be irrelevant in most divisions. Bout winners tend to be younger than losers, particularly in divisions displaying more diverse skill requirements. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
6. Strength and Conditioning (S&C) Practices of Judo Athletes and S&C Coaches: A Survey-Based Investigation.
- Author
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Weldon, Anthony, Cloak, Ross, Kirk, Christopher, Ruddock, Alan, Langan-Evans, Carl, Detanico, Daniele, Loturco, Irineu, and Kons, Rafael
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PROFESSIONAL practice ,ELITE athletes ,SPORTS injuries ,PHYSICAL training & conditioning ,COACHES (Athletics) ,DESCRIPTIVE statistics ,STRENGTH training ,THEMATIC analysis ,MUSCLE strength ,RESISTANCE training ,PHYSICAL fitness ,MARTIAL arts ,EVIDENCE-based medicine ,ATHLETIC ability ,PSYCHOSOCIAL factors - Abstract
The benefits of strength and conditioning (S&C) for improving judo performance and reducing injuries have been widely studied. However, the S&C practices used and perspectives held by those delivering S&C have yet to be elucidated. Therefore, this study investigated the S&C practices and perspectives of judokas and S&C coaches working within judo. Forty-two judokas and 9 S&C coaches completed an online survey comprising 6 sections: (a) written informed consent; (b) background information; (c) education, qualifications, and prescription; (d) views on S&C (e) exercise selection; and (f) issues and improvements. Frequency analysis was used to report responses to fixed-response questions and thematic analysis for open-ended questions. Results indicated that S&C coaches were primarily responsible for delivering S&C programs (60%), and S&C information was predominantly sourced from S&C coaches (43%). Strength and conditioning was deemed very important for randori (78-88%), overall judo performance (67-79%), and judo fitness (62-78%). Similarly, S&C was considered very important for the development of speed and power (76-89%), strength (71-89%), and injury reduction (69-78%). Novel findings were also observed, such as integrating judo-specific training within S&C practice, which may be partly explained by more S&C coaches holding judo belts (67%) than S&C qualifications (11%). This study supports practitioners delivering S&C in judo by offering a base of information to critique or align with their existing S&C practices and perspectives. Furthermore, our results may help identify potential gaps between methods used, proposed guidelines, and actual practice, facilitating the development of research and education resources tailored to the current climate. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
7. Proteasome composition in immune cells implies special immune‐cell‐specific immunoproteasome function.
- Author
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Inholz, Katharina, Anderl, Janet L., Klawitter, Moritz, Goebel, Heike, Maurits, Elmer, Kirk, Christopher J., Fan, R. Andrea, and Basler, Michael
- Abstract
Immunoproteasomes are a special class of proteasomes, which can be induced with IFN‐γ in an inflammatory environment. In recent years, it became evident that certain immune cell types constitutively express high levels of immunoproteasomes. However, information regarding the basal expression of proteolytically active immunoproteasome subunits in different types of immune cells is still rare. Hence, we quantified standard proteasome subunits (β1c, β2c, β5c) and immunoproteasome subunits (LMP2, MECL‐1, LMP7) in the major murine (CD4+ T cells, CD8+ T cells, CD19+ B cells, CD11c+ dendritic cells, CD49d+ natural killer cells, Ly‐6G+ neutrophils) and human immune cell (CD4+ T cells, CD8+ T cells, CD19+ B cells, CD1c+CD141+ myeloid dendritic cells, CD56+ natural killer cells, granulocytes) subsets. The different human immune cell types were isolated from peripheral blood and the murine immune cell subsets from spleen. We found that proteasomes of most immune cell subsets mainly consist of immunoproteasome subunits. Our data will serve as a reference and guideline for immunoproteasome expression and imply a special role of immunoproteasomes in immune cells. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
8. The International Olympic Committee framework on fairness, inclusion and nondiscrimination on the basis of gender identity and sex variations does not protect fairness for female athletes.
- Author
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Lundberg, Tommy R., Tucker, Ross, McGawley, Kerry, Williams, Alun G., Millet, Grégoire P., Sandbakk, Øyvind, Howatson, Glyn, Brown, Gregory A., Carlson, Lara A., Chantler, Sarah, Chen, Mark A., Heffernan, Shane M., Heron, Neil, Kirk, Christopher, Murphy, Marie H., Pollock, Noel, Pringle, Jamie, Richardson, Andrew, Santos‐Concejero, Jordan, and Stebbings, Georgina K.
- Subjects
MUSCLE anatomy ,SEXISM ,TESTOSTERONE ,GENDER identity ,WOMEN ,MUSCLE strength ,SPORTS events ,TRANS women ,COMMITTEES ,ATHLETIC associations - Abstract
The International Olympic Committee (IOC) recently published a framework on fairness, inclusion, and nondiscrimination on the basis of gender identity and sex variations. Although we appreciate the IOC's recognition of the role of sports science and medicine in policy development, we disagree with the assertion that the IOC framework is consistent with existing scientific and medical evidence and question its recommendations for implementation. Testosterone exposure during male development results in physical differences between male and female bodies; this process underpins male athletic advantage in muscle mass, strength and power, and endurance and aerobic capacity. The IOC's "no presumption of advantage" principle disregards this reality. Studies show that transgender women (male‐born individuals who identify as women) with suppressed testosterone retain muscle mass, strength, and other physical advantages compared to females; male performance advantage cannot be eliminated with testosterone suppression. The IOC's concept of "meaningful competition" is flawed because fairness of category does not hinge on closely matched performances. The female category ensures fair competition for female athletes by excluding male advantages. Case‐by‐case testing for transgender women may lead to stigmatization and cannot be robustly managed in practice. We argue that eligibility criteria for female competition must consider male development rather than relying on current testosterone levels. Female athletes should be recognized as the key stakeholders in the consultation and decision‐making processes. We urge the IOC to reevaluate the recommendations of their Framework to include a comprehensive understanding of the biological advantages of male development to ensure fairness and safety in female sports. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
9. Fair and Safe Eligibility Criteria for Women's Sport.
- Author
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Tucker, Ross, Hilton, Emma N., McGawley, Kerry, Pollock, Noel, Millet, Grégoire P., Sandbakk, Øyvind, Howatson, Glyn, Brown, Gregory A., Carlson, Lara A., Chen, Mark A., Heron, Neil, Kirk, Christopher, Murphy, Marie H., Pringle, Jamie, Richardson, Andrew, Santos‐Concejero, Jordan, Christiansen, Ask Vest, Jones, Carwyn, Alonso, Juan‐Manuel, and Robinson, Rebecca
- Subjects
SERIAL publications ,TESTOSTERONE ,SEX chromosomes ,SPORTS participation ,SPORTS events ,SEX (Biology) ,ATHLETIC ability ,SOCIAL support ,SEX determination ,ATHLETIC associations - Abstract
The article addresses the renewed debate over eligibility criteria for women's sports following controversies at the Paris 2024 Olympics, where athletes with alleged male advantages competed in the female category. Topics discussed include the necessity of excluding male advantages for fair competition, the limitations and ethical concerns of past sex verification methods, and the proposal for modern genetic screening as a solution to ensure fair and safe participation in female sports.
- Published
- 2024
- Full Text
- View/download PDF
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