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The purpose of this field study was to examine gender differences in the sweat response reported in the literature in trained men and women during indoor cycling. In the present study, 14 men and 12 women took part in a 90-minute spinning class in preparation for a 108-km road race. Delta body mass, corrected for the volume of water consumed, was used to estimate sweat loss during the exercise period. Men had a significantly higher sweat rate (1.12 L.h(-1)) compared to women (0.57 L.h(-1)), despite the fact that there were no significant gender differences in ad libitum fluid intake. Future research should focus on determining whether women may be more efficient in sweat production and evaporation and whether men may have a greater reserve capacity for increased sweating.
Journal of Strength and Conditioning Research, 2006, 20(3), 723–724
2006 National Strength & Conditioning Association Research Note
T. H
Department of Physiology, University of Pretoria, Pretoria, South Africa.
.Hazelhurst, L.T., and N. Claassen. Gender differ-
ences in the sweat response during spinning exercise. J. Strength
Cond. Res. 20(3):723–724. 2006.—The purpose of this field study
was to examine gender differences in the sweat response re-
ported in the literature in trained men and women during indoor
cycling. In the present study, 14 men and 12 women took part
in a 90-minute spinning class in preparation for a 108-km road
race. Delta body mass, corrected for the volume of water con-
sumed, was used to estimate sweat loss during the exercise pe-
riod. Men had a significantly higher sweat rate (1.12 L·h
) com-
pared to women (0.57 L·h
), despite the fact that there were no
significant gender differences in ad libitum fluid intake. Future
research should focus on determining whether women may be
more efficient in sweat production and evaporation and whether
men may have a greater reserve capacity for increased sweating.
. sweat production, gender, indoor cycling, cycle er-
Comparative studies of thermoregulatory re-
sponses in men and women have not produced
consistent results. Although gender-related dif-
ferences in thermoregulation have been attri-
buted to (a) morphological differences, (b) differing sweat-
ing responses and mechanisms, and (c) cardiac systemic
differences, some studies have reported similar thermo-
regulatory responses in both genders (1).
Spinning is an indoor group cycling exercise that com-
bines an aerobic and anaerobic workout on a modified
ergometer. Ambient conditions, particularly lack of wind
flow in the indoor spinning studio, promote an increase
in water vapor as sweat is vaporized. Previous research
has shown that indoor laboratory conditions resulted in
a 36–38% increase in sweat rate compared to simulated
outdoor conditions (4).
The aim of this study was to attempt to verify and
quantify gender differences in the sweat response report-
ed in the literature during 90 minutes of spinning exer-
Experimental Approach to the Problem
The current field study was designed to compare gender
differences in the sweat response while subjects were cy-
cling in an indoor setting. In order to address the aims of
the study, it was necessary to estimate sweat rate during
the exercise and to determine the morphology of the par-
ticipants. Men and women preparing for a 108-km cycling
event were allowed to drink water ad libitum during a
90-minute training session at a local spinning studio.
Sweat volume was estimated from the change in semi-
nude body mass corrected for the volume of fluid con-
sumed (7).
A total of 26 subjects, 14 men (age 38.7 years; height
1.82 m; mass 83.57 kg; body surface area 2.06 m
body mass index 25.5 kg·m
) and 12 women (age
33.9 years; height 1.65 m; mass 60.90 kg; body sur-
face area 1.68 m
; body mass index 22.23 kg·m
took part in this study. Participants attended at least 2
spinning classes a week and trained for a minimum of 3
hours a week on a road bicycle. It was assumed that the
spinners were fit and at least partially heat acclimatized,
as they were training in preparation for an upcoming na-
tional race. Subjects signed an informed consent after be-
ing given instructions on the study to be undertaken. The
study had been approved by the Ethics Committee of the
Faculty of Medicine, University of Pretoria (S 139/2001).
Experimental Procedures
Testing took place in the late afternoon at a spinning stu-
dio with 9 overhead fans. Each participant subjectively
modified exercise intensity by adjusting the flywheel re-
sistance on a scale of 1 to 10. Various exercise intensities
(i.e., climbing a hill, sprinting, or pacing with the bunch)
were achieved by adjusting the flywheel resistance on the
spinning cycle at the command of the instructor.
Sweat loss was calculated from seminude body mass
measured on an electronic scale (Toledo, Worthington,
OH) with an accuracy of 0.02 kg. Volume of sweat pro-
duced was estimated from the change in body mass mea-
sured directly pre- and postexercise. The value was cor-
rected for the volume of fluid ingested during the class,
determined by the change in mass of the water bottle pre-
and postexercise. Subjects emptied their bladders before
determining pre-exercise mass.
Statistical Analyses
Two-sample t-tests were used to discern any significant
differences between the means for gender characteristics
and sweat loss. All analyses were performed using the
Statistix (version 8.0; Analytical Software, Tallahassee,
FL) software package. Statistical significance was set at
A significant gender differences in mass and height re-
sulted in a significant difference in body surface area,
body surface area to mass ratio, and body mass index.
There was, however, no significant age difference be-
tween the genders.
Table 1 illustrates the gender differences in the sweat
response as a result of 90 minutes of spinning exercise.
There was a significant difference in the change of mass
from pre-exercise values. The average body mass of wom-
724 H
1. Change in mass, fluid ingested, and sweat loss of
men and women following 90 minutes of spinning.
Mean (SD)
Mean (SD)
Body mass (kg) 0.58 (0.89) 0.35 (0.63)*
Fluid ingested (L) 1.20 (0.30) 1.26 (0.62)
Sweat volume (L) 1.77 (0.71) 0.91 (0.41)*
Sweat rate (L·h
) 1.12 (0.45) 0.57 (0.26)*
Percentage sweat loss (%) 2.16 (0.91) 1.49 (0.65)*
* Significant gender difference (p0.05).
en increased from the pre-exercise mass, and the average
body mass of men decreased significantly from pre-exer-
cise levels. This resulted in a significant gender difference
in sweat rate. There was no significant gender difference
in the volume of fluid consumed during the class.
The 90 minutes of exercise performed resulted in a sweat
rate of 1.12 L·h
for men and 0.57 L·h
for women (Table
1). This difference occurred despite the fact that men and
women consumed similar volumes of fluid ad libitum.
Similar significant differences in sweat response of men
and women have also been reported by other investiga-
tors (2, 8, 9–13).
Anthropometrically, men and women differed signifi-
cantly in terms of height and mass, resulting in a signif-
icant difference in body surface area, body surface area
to mass ratio, and body mass index. Women generally
have a smaller body mass and body surface area, com-
pared with men, but they typically have larger surface
area-to-mass ratios. In the present study, men had a sig-
nificantly smaller body surface area-to-mass ratios (248
) compared to women (279 cm
). Since ex-
ercise heat production is proportional to body mass, and
since heat loss is a function of body surface area, women
would generate less heat and be able to dissipate more
than men for the same relative exercise intensity (2, 6).
In humid environments, women may reduce sweat
loss to a rate approximating the required rate of evapo-
ration through a reduction in the number of active sweat
glands, thus reducing wasted sweat (9–11). Lower sweat
response in women may also be related to suppression of
excessive sweat output, implying that women have a
more sensitive feedback from the wetted skin surface to
prevent excessive dripping of sweat (2). The higher sweat
gland density of women (5) results in smaller and closer
sweat droplets, allowing for a more economical sweating
pattern (3).
Men, however, recruit relatively fewer sweat glands
than women, indicating that men have a greater reserve
capacity for further increasing sweating, should it be re-
quired (9–11). The larger volume of sweat produced per
gland by men (5) (i.e., drops that are larger and further
apart) could provide better evaporative cooling in envi-
ronments in which dry air temperature is close to skin
temperature and evaporative cooling is the main source
of heat loss (3).
Future research in a controlled laboratory setting
should, then, focus on determining whether women have
superior feedback mechanisms to control sweat produc-
tion and to therefore limit dehydration.
This study has shown that both men and women leave a
spinning studio partially dehydrated. Men lost 2.2%
and women 1.5 % of their initial body mass as a result
of sweat production. Men and women partaking in spin-
ning exercise must be informed that different hydration
protocols need to be followed during and after their clas-
ses because of the differences in sweat response.
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I.B. M
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Address correspondence to Dr. Nicolaas Claassen,
... In contrast, Hamouti et al. (2011) found no differences in sweat sodium between aerobically trained subjects and aerobically untrained subjects if values were normalized for sweat rate. Hazelhurst and Claassen (2006) reported higher sweating rates in males than females during physical exercise with fluid intake. These studies indicated that heat acclimation and sex should to be considered if sweat markers are used for dehydration diagnosis, whereas different levels of aerobic fitness may not constitute a confounding factor. ...
... Sweat chloride, sweat osmolality, and sweat sodium were demonstrated to facilitate dehydration diagnosis after 2 h of physical exercise (Morgan et al. 2004). Some factors that might confound this diagnostic potential were already studied, for example, heat acclimation (Buono et al. 2007), aerobic capacity (Hamouti et al. 2011), and sex (Hazelhurst and Claassen 2006). Moreover, regional sweat markers could be successfully converted into whole-body sweat markers (Baker et al. 2009a(Baker et al. , 2011Patterson et al. 2000). ...
... Future studies may therefore include subjects of a wider range of ages. The sweatbased approach will likely be influenced by heat acclimation (Buono et al. 2007), sweat rate differences between females and males (Hazelhurst and Claassen 2006), and diseases that affect sweat composition. For example, cystic fibrosis which leads to excessive chloride and sodium concentrations (Tortora and Derrickson 2009, Chapter 23). ...
Full-text available
Prolonged physical exercise is often accompanied by mild to severe dehydration. Marathon runners, as an extreme example, can lose up to 14 % of their total body water (TBW) during races in warm environments. This excess of TBW loss is considered close to life-threatening. But also moderate TBW loss can impair aerobic endurance, muscular strength, and cognitive performance. In this light, the present thesis proposes three machine learning approaches for quantitative estimation of TBW loss and two theoretical approaches for efficient, nonlinear machine learning. The former approaches support the accurate diagnosis of exercise-induced dehydration as well as recommendations on fluid intake for rehydration. The latter approaches could contribute to future wearable devices for TBW monitoring, although they are not exclusively applicable to this context. The first machine learning approach utilizes core and skin temperature to correct corrupted bioimpedance measurements, which often occur because of confounding factors during physical exercise. It therefore enables the usage of the noninvasive and portable bioimpedance technology for TBW loss estimation during physical exercise. The second machine learning approach explores the potential of sweat chloride and sweat osmolality for dehydration diagnosis. It reveals correlations between the two sweat markers and TBW loss, and it proposes quantitative TBW loss estimations based on the sweat markers. The third machine learning approach synthesizes information from seven salivary markers (amylase, chloride, cortisol, cortisone, osmolality, potassium, total proteins). It demonstrates that salivary markers provide sufficient information for quantitative TBW loss estimation, which extends previous saliva-based classifications between euhydrated and dehydration individuals. All three approaches were evaluated using measurements that were collected from ten subjects after eight consecutive, 15 min intervals of physical exercise. Among several insights, like nonlinearly increasing salivary markers during progressive dehydration, the evaluation highlighted that TBW loss estimations could be achieved with an accuracy of 0.34 l, which corresponds to about a glass of water. This accuracy was achieved using salivary markers and nonlinear machine learning. The first theoretical approach weaves the powerful kernel machinery into branch and bound (B&B) feature selection. It facilitates the recognition of complex and nonlinear data structures using the efficient B&B search method. The second theoretical approach introduces an approximation of the Gaussian radial basis function (RBF) kernel for the efficient computation of nonlinear classification decisions. It also illustrates the close relationship between the kernel approximation and the reproducing kernel Hilbert space (RKHS) that is being approximated. Both approaches were evaluated on benchmark data sets, which illustrated that they constitute valuable alternatives to state-of-the-art methods. In summary, nonlinear processing of salivary markers facilitated the most accurate TBW loss estimations, and the theoretical approaches enhanced the toolbox of efficient and nonlinear machine learning. A combination of both contributions could therefore constitute the foundation for efficient, nonlinear processing of the physiological measurements and markers, which would in turn be prerequisite to develop energy-efficient, unobtrusive wearable devices for TBW monitoring.
... En relación a la figura del instructor de C.I., consi-deramos que es de importancia dilucidar aspectos relacionados con su formación y sus condiciones de trabajo, puesto que éstos pueden tener influencia directa en su praxis. Su tarea es de responsabilidad, puesto que las sesiones de C.I. suelen ser de alta intensidad, y diversos estudios han demostrado que se queman cantidades significativas de calorías (Ainsworth, Haskell, Whitt, Irwin, Swartz, Strath, O Brien, Bassett, Schmitz, & Emplaincourt, 2000), que hay grandes pérdidas de líquidos (Hazelhurst & Claassen, 2006), y que las temperaturas corporales sufren grandes aumentos (Ramos-Jiménez, Hernández-Torres, Wall-Medrano, Torres-Durán, Juárez-Oropeza, Viloria & Villalobos-Molina, 2014). Estas condiciones de práctica reúnen factores de riesgo para el desarrollo de diversos problemas de salud o lesiones, como podría ser el caso de la rabdomiolisis (Brogan, Ledesma, Coffino, & Chander, 2017), por citar algún ejemplo. ...
... Boned et al. (2015) señalan que el perfil sociodemográfico del profesional del fitness español se caracteriza por presentar una edad media de 32 años. Según Alves, da Costa, Castañer, Fernándes y Anguera (Alves et al., 2013), esta media es de 25,4 años, puntualizando que en estos estudios se hacía referencia a cualquier profesional del fitness, no refiriéndose de forma específica a los instructores de C.I. En una actividad como el C.I., que conlleva un alto compromiso fisiológico (Ainsworth et al., 2000;Hazelhurst & Claassen, 2006;Ramos-Jiménez et al., 2014), y basada en la reproducción de modelos, es lógico que encontremos una edad media y máxima de los profesionales que la imparten no demasiado elevada. ...
Full-text available
El Ciclo Indoor (C.I.) es una de las actividades con mayor demanda en la actualidad, y en las últimas décadas se ha implantado en la mayoría de los centros de Fitness y gimnasios de gran parte del mundo. Nuestro objetivo es conocer el perfil profesional del instructor de C.I. en España, así como aspectos relacionados con su metodología de trabajo y sus condiciones laborales. Los 57 participantes que conformaron la muestra y que procedían de diferentes lugares de España, ocupaban el puesto de instructor de C.I. en el momento de la investigación, siendo encuestados a partir de un instrumento diseñado ad hoc. Se ha empleado una metodología cuantitativa de corte descriptivo. Aunque no podemos constatar que sea una muestra representativa, los datos apuntan a que su perfil es el de un varón de aproximadamente 35 años, con más de 5 años de experiencia, que imparte también otras actividades dirigidas, y trabaja por cuenta ajena. Imparte entre 6 y 7 sesiones de C.I. semanales y existe gran disparidad en cuanto a su nivel y tipo de formación. Abstract. Indoor Cycling (I.C.) is one of the activities with the greatest demand nowadays, and in recent decades, it has been implemented in most fitness centers and gyms in a large part of the world. Our objective is to know the I.C. instructor's professional profile in Spain, as well as other aspects related to their work methodology and working conditions. The respondents were 57 instructors from different parts of Spain (the country), all of them occupying the position of I.C. instructors. They were surveyed based on an instrument designed ad hoc. A quantitative cutting methodology has been used. Although it is not a representative sample, the data suggest that its profile is that of a male of approximately 35 years old, with more than 5 years of experience, who also teaches other directed activities, and works for others. He teaches between 6-7 sessions of C.I. weekly. There is great disparity in terms of their level and type of training.
... Spinning çalışmalarının yaşlı ve sedanter bireylerin kalbi zorladığına yönelik çıkarımlar olmasına karşın, genç ve orta yaşlı bireylerde kardiyovasküler sağlık ve vücut kompozisyonu üzerine olumlu etkileri olduğunu bildiren çalışmalar bulunmaktadır. [10][11][12] Verrusio ve ark. nın yaptığı çalışmada 50-69 yaş arası bireylerde diyetle birlikte uygulanan spinning çalışmalarının, terapi ve diyet, standart fiziksel aktivite ve diyet gruplarına göre bel çevresi, beden kitle indeksi, kalp atım hızı (KAH) ve kan yağlarında azalmalar, glikoz metabolizmasında da olumlu gelişmeler sağladığı bildirilmiştir. ...
... In studies on the effectiveness of cycling, it is emphasized that an adequate load can be provided due to a wide range of variations in pedal frequency and resistance level [9,10]. Researchers have studied the features of thermoregulation and changes in lactate level after IC training, and the optimal parameters for the intensity of training were identified [11,12,13,14]. The feasibility and effectiveness of applying IC programs in women of different ages, based on the optimization of physical activity and the selection of special exercises depending on the parameters of their functional state and the presence of diseases, have also been investigated [15,16]. ...
Full-text available
Introduction. Indoor cycling training programs at fitness clubs offer the possibility of optimizing the structure and amount of physical activity, which reduces the risk of disrupting the adaptive abilities of women’s bodies. The main purpose of this study was to identify the effect of an indoor cycling program on the body composition and physical fitness of young women. Material and methods. Twenty-nine women (age = 29.31 ± 3.40 years, body weight = 70.71 ± 6.15 kg, and height = 169.83 ± 3.17 cm) took part in the study, participating in three classes per week for 16 weeks. Each class included three periods: the preparatory, main, and supporting periods. Body composition (waist circumference and body mass index), cardiorespiratory fitness (VО2max), motor fitness (balance), and musculoskeletal fitness (upper and lower body muscle strength and muscular endurance) were compared before the beginning of the study and after 10 and 16 weeks of training. Changes recorded in each variable over time were analyzed statistically using repeated measures methods. Results. Significant improvements in physical fitness were identified in the values of the body mass index (7.81%; ES: 0.95, p = 0.0001) and VО2max (12.51%; ES: 1.02, p = 0.0001). Moderate improvements were found in lower body muscle strength (11.13%; ES: 0.66, p = 0.0001) and waist circumference (6.05%, ES: 0.65, p = 0.0001). There was an increase in the strength of the muscles of the upper body (5.27%; ES: 0.41, p = 0.0001), muscular endurance (8.20%; ES: 0.32, p = 0.0001), and balance (10.68%; ES: 0.29, p = 0.003). Conclusion. Indoor cycling in a fitness club is an effective form of exercise for young women; it has targeted training effects on the body’s functional systems, adaptive abilities, and physical fitness.
... Previously, Ramos-Jiménez et al. [54] demonstrated that dehydration during exercise induces physiological stress. Based on the literature, some authors suggest that the sweating rate is higher in male compared to female athletes [55,56]. Nevertheless, others proposed that women take more time than men to begin sweating [57]. ...
Background In order to provide additional information on the behaviour of biochemical parameters related to stress responses to a specific long-term competition, we aimed to compare the stressful effects of a long-lasting competition on physiological variables in men and women. Methods This is a prospective observational analytical study. Twenty-five professional athletes, 15 men and 10 women, travelled 460 km for 4 days in an international edition of the Ecomotion/Pro AR World. Results After the competition, we detected an increase in α-amylase and cortisol levels and a decrease in salivary immunoglobulin A (lgA) levels. The relative percentage changes in α-amylase, IgA and cortisol levels were significantly higher in women than in men, whereas women had lower relative percentage changes in glucose and lactate levels compared with men. There was a decrease in lymphocyte, eosinophil and monocyte counts, with relative percentage decreases in lymphocytes and monocytes being significantly higher in female athletes than in males. There were increases in the serum activities of total creatine kinase (CK), the creatine kinase myocardial isoform (CKMB), alanine aminotransferase (ALT), aspartate aminotransferase (AST) and lactate dehydrogenase (LDH) at the end of the test, with significantly higher elevations of total CK, CKMB and LDH in men and ALT in women. Conclusion Long-lasting competition induced stress, muscle damage, anaemia and changes in the immune system. Women had more intense responses of cortisol and leukocytes.
... Wynikają one między innymi z większego stosunku powierzchni ciała kobiet do jego masy, większej ilości podskórnej tkanki tłuszczowej u kobiet, mniejszej ich zdolności wysiłkowej czy fazy cyklu menstruacyjnego [359]. Reakcja pocenia w odpowiedzi na wysiłek fizyczny występuje w mniejszym stopniu u kobiet niż u mężczyzn [359,360]. Natomiast nie zaobserwowano między przedstawicielami obu płci różnic dotyczących utraty elektrolitów w pocie [361]. Badania Appenzeller'a i wsp. ...
Physical activity favours the maintenance of an optimum psychomotor condition and, in the process of rehabilitation, is an important factor supporting the return to full health understood as a simultaneous physical and psychological well-being. A connection exists between the activity of skeletal muscles and undisturbed functioning of the central nervous system regarding psychological functions, which is the object of many contemporary studies. To-date, no analyses have been performed of a simultaneous effect of physical exercises on the transformations in the kynurenine pathway and psychological functioning, including the control of expression of negative emotions and actions undertaken in stressful situations. The objective of the conducted study is the confirmation of the presence of the key metabolites of the kynurenine pathway (tryptophan, kynurenine, and kynurenic acid) in sweat, determination of changes in the content in sweat under the effect of physical activity, and their compilation with psychological functioning. Considering the adopted goal, a hypothesis was posed that changes in the content of kynurenine pathway metabolites and the selected aspects of psychological functioning will occur in the examined persons during their participation a cycle of regular intensive and controlled physical activity. The study group consisted of 35 patients with the diagnosis of mild inefficiency due to back pain, who received rehabilitation in the Rehabilitation Centre at the Institute of Rural Health in Lublin. The patients in the study had sweat collected for biochemical determinations three times during a 28-day training cycle on a cycle ergometer and cross-trainer – before starting the exercises, on the day 14 and day 28. During this procedure two different methods were simultaneously used – collection of sweat by means of an absorption pad from the interscapular region, and collection of a drop of sweat from the forehead region. Quantitative determinations of tryptophan, kynurenine, and kynurenic acid were performed using high performance liquid chromatography with ultraviolet and fluorescence detection, whereas the determinations of sodium, potassium, magnesium and calcium were carried out by the method of inductively coupled plasma collision/reaction cell ionization mass spectrophotometry. In addition, the patients were subjected to psychological examinations twice, on the first day and day 28 of the training cycle, using the Multidimensional Coping Inventory (COPE) and the Courtauld Emotional Control Scale (CECS). The conducted analyses for the first time confirmed that human sweat contains tryptophan, kynurenine, and kynurenic acid. Based on Wpływ aktywności fizycznej na przemiany szlaku kynureninowego... 170 the comparative analysis of changes in the content of sodium, potassium, magnesium, and calcium, the indications in literature were confirmed suggesting that the amount of sodium in a single sweat sample is a stable indicator of the amount of sweat collected. This allowed a quantitative assessment of changes in the content of tryptophan, kynurenine, and kynurenic acid during the training cycle by referring the content of these metabolites to the amount of sodium in a sample. It was observed that physical exercises favour a decrease in the amount of kynurenine, and an increase in the amount of kynurenic acid in sweat, which is manifested on day 14, while normalization occurs on day 28 of training. It was proven that physical exercises result in a long-term increase in the kynurenine transaminase activity responsible for the formation of kynurenic acid from kynurenine. In the sphere of psychological functioning, the completion of a 28-day cycle of physical exercises resulted in an increased frequency of application of strategies for coping with stress, consisting in the planning, seeking instrumental support, as well as positive revaluation and development. The results of research obtained suggest that the changes observed in psychological functioning may result from changes in the activity of kynurenine pathway enzymes, and the discovered dynamics of biochemical changes indicates a high effectiveness of the 14-day cycle of systematic physical exercises in the rehabilitation process.
... In terms of ambient conditions, an indoor studio where there is no wind flow is preferred for this form of exercise. It is usually performed in dimly-lit studios and on stationary ergometers keeping up with the rhythm of music [1,2]. Also, Spinning ® can be modified in order to be used by performance athletes in addition to exercise performed for the maintenance of health. ...
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The aim of the study was to examine the changes in the acute blood lactate levels of elite taekwondo players when carrying out high-intensity interval training on Spinning ® bikes. Twenty elite-level taekwondo athletes participated in the study. The subjects were selected from athletes who had been competitors for at least six years. Their average age, height and weight values were determined to be 18.89±2.07 years, 176.8 ± 8.73 cm and 70.59 ± 12.13 kg respectively. In the present study the subjects carried out high-intensity interval training using Spinning bikes based on the Tabata protocol. The loads were applied as a total of four sets of eight repetitions with the principle of 20 seconds of load followed by 10 seconds of rest with one-minute's rest given between sets. The subjects' lactate levels were measured from their fingers using the Accutrend Lactate portable lactate analyzer with the help of the strips provided. Lactate measurements were made five times: before training (Pre), after Set 1 (1S), after Set 2 (2S), after Set 3 (3S) and once the exercise was over (Post). The heart rates (HR) of the athletes were monitored by their coaches before and during exercise. The data were analyzed using One Way ANOVA in the SPSS 22 package program. A statistically significant difference was found among the baseline lactate levels, the 1S, 2S, 3S and post lactate levels in the study (p<0.05). There was a statistically significant difference when the 1S lactate level was compared with all the time periods except for 2S (p<0.05). The difference between the 3S and Post lactate levels was not statistically significant (p> 0.05). As a result of the study it was observed that Spinning ® training carried out using the high-intensity interval training method caused a rapid increase in acute lactic acid accumulation. In the case of performance athletes, we can say that this exercise could be part of the lactate tolerance training used to counter fatigue.
While earlier studies have attempted to resolve the challenges encountered when interpreting gamma-hydroxybutyric acid (GHB) concentrations in hair (primarily due to its endogenous presence), few have had large sample sizes. The first objective of this study was to evaluate the inter-individual variation of endogenous GHB concentrations. The second objective, to be detailed in another report, was to assess intra-individual variation and the impact on exogenous GHB discrimination. Over 2000 hair segments from 141 women and 73 men (all processed hair 3-12 cm long) were analyzed in this study. The raw calculated range of endogenous GHB concentrations was < 0.40-5.47 ng/mg with 97.5% of the segmental results calculated less than 2.00 ng/mg. Imputation, assuming a lognormal distribution, was applied to the data to include non-detect data (<LOQ), which led to an estimated endogenous GHB range of 0.16-5.47 ng/mg. Kruskal-Wallis tests were employed on a segmental basis for group comparisons. This test was applied to the male and female segmental medians and subsequently indicated that these groups were different at the α = 0.05 level of significance. Additionally, female hair samples appeared to have a trend comprising higher endogenous GHB concentrations close to the scalp and a mean net decrease of ~ 0.2-0.3 ng/mg distally. Male hair samples displayed the opposite trend, with a mean net increase of ~ 0.5-0.6 ng/mg from the proximal to the distal end of the hair shaft. It was also concluded that differences exist between the median GHB concentrations of the "treated" and "untreated" hair in the female group at the α = 0.05 level of significance. Age groups and races were analyzed, but none of the observed differences in median concentration were significant at α = 0.05. This is the largest endogenous GHB hair population study to date and provides substantial new data on inter-individual variation and chronological trends of GHB concentrations in hair.
This study investigated the effects of a menthol mouth rinse on performance and physiological responses in female cycling athletes during a 30-km individual time trial (ITT). Participants (n=9) cycled for 30-km in hot conditions (30 ± 0.6 °C, 70 ± 1% relative humidity, 12 ± 1 km/h windspeed) on two test occasions using a menthol (MEN) mouth rinse (MR) occurring every 5 km. Perceptual responses (perceived exertion and thermal perception) were recorded at 5, 10, 15, 20, 25, and 30-km. The MEN MR significantly improved ITT performance by 2.3 ± 2.7% relative to PLA (p= 0.034, d= 0.85, 95% CI= 8.43 to 166.9). There were no significant differences in perceived exertion and thermal perception. These results demonstrate that a non-thermal cooling agent can improve physiological performance in moderately trained female cyclists with no change in perceived exertion or thermal perception. iii Acknowledgements
Following a request from the European Commission, the Panel on Dietetic Products, Nutrition and Allergies (NDA) derived Dietary Reference Values for zinc, using a two-stage factorial approach and reference values for body weight. The first stage of estimating physiological requirements used studies that had physiologically plausible data, specifically related to faecal excretion of endogenous zinc. Adult physiological requirements were closely related to body size, and sex differences were not detectable after adjustment for body weight. Average Requirements (ARs) for dietary zinc necessary to meet physiological requirements were estimated using saturation response modelling, taking into account the inhibitory effect of dietary phytate on zinc absorption. Estimated ARs and Population Reference Intakes (PRIs) are provided for phytate intake levels of 300, 600, 900 and 1 200 mg/day, which cover the range of mean/median intakes observed in European populations. ARs range from 6.2 to 10.2 mg/day for women with a reference weight of 58.5 kg and from 7.5 to 12.7 mg/day for men with a reference weight of 68.1 kg. PRIs were derived from the zinc requirement of individuals with a body weight at the 97.5th percentile for reference weights for men and women and range from 7.5 to 12.7 mg/day for women and from 9.4 to 16.3 mg/day for men. ARs for infants from seven months of age and for children were estimated factorially, based on extrapolation from estimates of adult losses plus zinc needs for growth, and range from 2.4 to 11.8 mg/day. PRIs for infants and children were derived by assuming a coefficient of variation of 10 %, and range from 2.9 to 14.2 mg/day. For pregnancy and lactation, additional zinc requirements related to fetal and maternal tissues and transfer of zinc into breast milk, respectively, were considered and additional PRIs of 1.6 and 2.9 mg/day, respectively, were estimated.
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Following an extensive anthropometric evaluation, thermoregulatory responses were studied in nine men and nine women who performed immersed exercise with post-exercise rest in 28°C water. During the post-exercise period esophageal temperature (T es), oxygen consumption, heat flux and skin blood perfusion were monitored at 10s intervals, with average minute values used for calculations. The ΔT es (relative to restingT es) at which sweating abated and shivering commenced were defined as the ΔT es thresholds for the cessation of sweating and onset of shivering, respectively. No significant gender differences were evident in the sweating and shivering threshold ΔT es values, or the magnitude of the null-zone. Usingz-tests for parallelism the rates of core cooling across the null-zone were not found to differ significantly between genders, nor were the slopes of the perfusion: ΔT es responses across the null-zone or the post-threshold shivering responses (ml·kg−1·min−1·°C−1). The slope of the sweating response (measured from immersion until sweat cessation; g·m−2·min−1°C−1) was, however, significantly lower in the female than in the male samples (z = 3.93;P < 0.01). Despite the gender-related dimorphic distribution of adipose tissue, both men and women lost equal proportions of their total heat flux from central and peripheral measurement sites. Performing a standardized regression using the rate of core cooling across the null-zone as the dependent variable and gender as a dummy variable, gender and adipose tissue mass were not found to be significant factors in determining the rate of core cooling, while mass (β = 1.73;P < 0.05) and muscle mass (β = 1.86;P < 0.05) did contribute significantly to the rate of core cooling. It was concluded that, except for the quantitative differences in the sweating response, men and women respond to deviations in core temperature in a similar manner, with mass and muscle mass modifying this response.
The extreme physical endurance demands and varied environmental settings of marathon footraces have provided a unique opportunity to study the limits of human thermoregulation for more than a century. High post-race rectal temperatures (Tre) are commonly and consistently documented in marathon runners, yet a clear divergence of thought surrounds the cause for this observation. A close examination of the literature reveals that this phenomenon is commonly attributed to either biological (dehydration, metabolic rate, gender) or environmental factors. Marathon climatic conditions vary as much as their course topography and can change considerably from year to year and even from start to finish in the same race. The fact that climate can significantly limit temperature regulation and performance is evident from the direct relationship between heat casualties and Wet Bulb Globe Temperature (WBGT), as well as the inverse relationship between record setting race performances and ambient temperatures. However, the usual range of compensable racing environments actually appears to play more of an indirect role in predicting Tre by acting to modulate heat loss and fluid balance. The importance of fluid balance in thermoregulation is well established. Dehydration-mediated perturbations in blood volume and blood flow can compromise exercise heat loss and increase thermal strain. Although progressive dehydration reduces heat dissipation and increases Tre during exercise, the loss of plasma volume contributing to this effect is not always observed for prolonged running and may therefore complicate the predictive influence of dehydration on Tre for marathon running. Metabolic heat production consequent to muscle contraction creates an internal heat load proportional to exercise intensity. The correlation between running speed and Tre, especially over the final stages of a marathon event, is often significant but fails to reliably explain more than a fraction of the variability in post-marathon Tre. Additionally, the submaximal exercise intensities observed throughout 42km races suggest the need for other synergistic factors or circumstances in explaining this occurrence There is a paucity of research on women marathon runners. Some biological determinants of exercise thermoregulation, including body mass, surface area-to mass ratio, sweat rate, and menstrual cycle phase are gender-discrete variables with the potential to alter the exercise-thermoregulatory response to different environments, fluid intake, and exercise metabolism. However, these gender differences appear to be more quantitative than qualitative for most marathon road racing environments.
Thermoregulatory and cardiorespiratory responses to bicycling 55 km (mean speed 9.7 m X s-1) outdoors (15 degrees C DB) were compared to equivalent cycle ergometry (90 min at 65% VO2max) in the laboratory (20-23 degrees C DB, 50% RH) in 7 trained cyclists. Outdoor environmental conditions were simulated with fans and lamps, and were contrasted with standard no-wind, no-sun laboratory conditions. Sweating rate was similar during outdoor and laboratory simulated outdoor cycling (0.90 and 0.87 to 0.94 1 X h-1 respectively). During outdoor bicycling, mean heart rate (161 bt X min-1) was 7-13% higher (p less than .05) than under laboratory conditions, suggesting a greater strain for a similar external work rate. The increase in rectal temperature (0.8 degrees C) was 33-50% less (p less than 0.05) at the cooler outdoor ambient temperature than in the laboratory. Thermoregulatory stress was greater under the no-fan, no-lamp laboratory condition than during simulated outdoor conditions (36-38% greater (p less than 0.05) sweating rate, 15-18% greater (p less than 0.01) mean skin temperature, 6.4 to 7.8 fold greater (p less than 0.01) amount of clothing-retrained sweat). The cooling wind encountered in actual road bicycling apparently reduces thermoregulatory and circulatory demands compared with stationary cycle ergometry indoors. Failure to account for this enhanced cooling may result in overestimation of the physiological stress of actual road cycling.(ABSTRACT TRUNCATED AT 250 WORDS)
Thirty male and twenty-six female Caucasians were tested at work levels of 1.0 liters O 2 consumption in 90 F wet-bulb temperature, 93 F dry-bulb temperature, and 80 ft/min air velocity for comparative heat reactions in the unacclimatized state. The females had more severe physiological and psychological reactions. Rectal temperatures of 104 F and heart rates of 180 beat/min were reached more rapidly than in the male. The females sweated less and their oxygen consumptions were lower than those of the males. Ten males and four females were then acclimatized to the same extent at the same work rate in 93 F wet-bulb temperature. At the end of the period their reactions were closely similar, although the females responded slower to the acclimatization procedure. Both groups ended with heart rates of 140 beat/min and rectal temperatures of 102 F. The females, however, continued to sweat less. In a retest at 90 F wet-bulb temperature, both groups had heart rates of 130–140 beat/min and rectal temperatures of 101 F. Females still sweated less. The results demonstrate the fact that females react more severely on exposure to severe heat and work conditions. Once acclimatized, however, the temperature and circulatory reactions of both sexes are closely similar, but the females sweat less than males. acclimatization of Caucasians to heat; Caucasians—acclimatization to heat; sex differences—heat reactions; physiological reactions to heat Submitted on September 14, 1964
Four acclimated men and four acclimated women exercised at 30% V̇O2(max) in a hot-humid environment [dry-bulb temperature (T(db))/wet-bulb temperature (T(wb)) = 37/30°C] and a hot-dry (T(db)) = 48°C, T(wb) = 25°C) environment. Variables recorded during heat stress tests, rectal temperature (T(re)), mean skin temperature, heart rate (HR), total body sweat rate (M(sw)), chest sweat rate (chest ṁ(sw)), sweat gland activity per unit surface area (ρSGA) on the chest, and sweat gland flow (SGF) on the chest were recorded. Sweating efficiency (η(sw)) was determined as the ratio of required to observed sweating. Maximum sweat gland activity per unit surface area (ρSGA(max)) was determined with the aid of methacholine. There were no differences between sexes or environments in T(re) or HR. Both sexes had significantly lower Ṁ(sw) and chest ṁ(sw) in the humid heat compared with the dry heat. The women maintained significantly lower Ṁ(sw) and chest ṁ(sw) than the men in the humid heat, with significantly higher η(sw). There were no differences in sweating rates of efficiency between sexes in the dry heat. Among the women, ρSGA relative to ρSGA(max) (%ρSGA(max)) and η(sw) were significantly higher in the dry heat than in the humid heat, but SGF was similar in both environments. Among the men, SGF was significantly higher in the dry heat than in the humid heat, and %ρSGA(max) and η(sw) were similar in the two environments. In both environments, the men recruited a significantly lower percentage of their available sweat glands than did the women. The reduction in ρSGA in the humid heat among the women allowed the women to conserve body water through improved sweating efficiency. However, the men had a larger apparent reserve to increase sweating in more severe dry heat.
Four men and four women with similar VO2max (56.33 +/- 4.05 and 54.08 +/- 4.27, respectively) exercised up to 3 h at 30% VO2max during heat stress tests (HST) before and after acclimation to dry heat [dry-bulb temperature (Tdb)/wet-bulb temperature (Twb) = 48/25 degrees C]. Rectal (Tre), tympanic sweat on the chest (msw), and total sweat rate (Msw) were recorded. There were no differences in the responses of the women between phases of the menstrual cycle. Tre, Tty, Tsk, and Tdb at the onset of sweating were similar in both sexes before and after acclimation. The nonacclimated men had significantly higher Msw and slower rise in Tre as compared to the nonacclimated women. Following acclimation these differences were no longer evident. Acclimation produced an increase in Msw in both sexes that was characterized by an increase in sweating sensitivity (delta msw/delta Tre). It was concluded that sex alone does not determine responses to heat stress. Consideration should also be given to the relative cardiovascular strain, state of acclimation, and the ambient conditions.
The major objective of this study was to determine whether sex-related differences in thermoregulation exist; and if so, whether there was any method to define these differences. A major methodological problem of the study was the inability to find groups of males and females matched in all their physical characteristics, namely: body weight, skin surface area, percentage of body fat and cardiorespiratory physical fitness. This problem was partially solved by dividing each sex into two subgroups and matching the subgroups as 'small' males vs. 'big' females, or more fit females vs. less fit males. The sex-related differences concluded from this investigation are summarized in Table 4. In comfortable climatic conditions (20 C, 40% rh) men and women reacted in a physiologically similar fashion. Under wet conditions, whether mild or hot, females tolerated the heat better than males. They displayed lower deep body and skin temperatures, and therefore lower heat storage, while demonstrating lower sweat rates and subsequently less dehydration than males. In contrast, under hot-dry conditions, males seemed to be at a physiological advantage. Compared to females, they showed lower deep body and skin temperatures, lower HR, lower heat storage, and similar sweat rates. (Author)