Effect of intense training on plasma leptin in male and female swimmers

Department of Exercise and Sport Science, East Carolina University, Greenville, NC, USA.
Medicine &amp Science in Sports &amp Exercise (Impact Factor: 3.98). 03/2001; 33(2):227-31. DOI: 10.1097/00005768-200102000-00009
Source: PubMed


The purpose of this study was to determine whether fasting plasma leptin concentration was altered with an increase in training volume in competitive male and female athletes.
Intercollegiate male (N = 9) and female (N = 12) swimmers were examined during the preseason and at two times during the mid-season (mid-season 1 and mid-season 2) when training volume was relatively high (33,000 m.wk(-1)). Body composition (hydrostatic weighing), energy intake and expenditure, and fasting plasma leptin concentration were measured.
In the women, there was a significant (P < 0.05) decline in fat mass (2 kg) with the increase in training volume, which was not accompanied by a reduction in fasting leptin (12.8 +/- 1.5 vs 11.0 +/- 1.2 vs 11.0 +/- 1.5 ng.mL(-1) for preseason, mid-season 1, and mid-season 2, respectively). In the men, there were no significant changes in body composition, body mass, or fasting leptin (4.4 +/- 0.8 vs 4.3 +/- 0.8 vs 4.6 +/- 0.8 ng.mL(-1), respectively).
These findings suggest 1) plasma leptin is not sensitive to an increase in training volume and 2) leptin may not be indicative of changes in fat mass with an increase in training volume in female athletes. These data suggest that leptin may not be useful in monitoring relative training stress in athletes.

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    • "It is hypothesized that hypoleptinemia occurs to compensate for inadequate EA (Hilton and Loucks 2000), such that reduced leptin concentrations are directly associated with secondary amenorrhea (Blüher and Mantzoros 2009) and reductions in IGF-1 and T3 concentrations (Chan and Mantzoros 2005; Welt et al. 2004). The effects of exercise on leptin are mediated primarily by exercise-induced changes in EA and body composition, and not by training itself (Noland et al. 2001; Kraemer and Castracane 2010). IGF-1 and T3 are required to ensure adequate growth and to obtain optimal bone density in adolescents (Rogol 2010). "
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    ABSTRACT: Previous intervention studies suggest that leptin, insulin, insulin-like growth factor 1 (IGF-1), and triiodthyronine (T3) are sensitive markers of inadequate energy intake in relation to exercise expenditures. Because of limitations in metabolic hormone measurements, self-reported energy availability (EA) based on food and activity records may present an alternative for characterizing energy status in young athletes. The purpose of the current study was to assess whether self-reported EA is related to leptin, insulin, IGF-1, and T3 in 352 young athletes. Sex, body composition, sport participation, and acute weight changes were considered as confounding variables. Multiple linear regression revealed that EA was negatively associated with leptin (p < 0.05) but not with insulin, IGF-1, or T3. Female athletes with low EA (<30 kcal·kg(-1) fat-free mass (FFM)) had higher leptin concentrations (5.0 ± 4.7 ng·mL(-1)) and more body fat (18.3% ± 5.1%) than did females with normal EA (leptin, 3.1 ± 2.4 ng·mL(-1); body fat, 15.8% ± 4.2%; both, p < 0.001). Athletes reporting acute weight loss (>1 kg·week(-1)) had a lower EA (18.9 ± 7.4 kcal·kg(-1) FFM) than did weight-stable athletes (30.0 ± 11.2 kcal·kg(-1) FFM) or athletes reporting weight gain (>1 kg; 49.7 ± 13.1 kcal·kg(-1) FFM). IGF-1 and T3 were also reduced in athletes who lost weight (p < 0.01). This cross-sectional study reveals a lack of association between self-reported EA and metabolic hormones indicative of energy status in young athletes. Further studies are needed to investigate whether self-reported EA and metabolic hormones are in better agreement when measured repeatedly.
    Applied Physiology Nutrition and Metabolism 07/2013; 38(7):725-33. DOI:10.1139/apnm-2012-0373 · 2.34 Impact Factor
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    • "Leptin has an anorexigenic role (Westerterp-Plantenga et al., 2001); its levels decrease under negative energy balance conditions (Mars et al., 2005; Pasiakos et al., 2011). It is also an extensively studied hormone in relation to energy homoeostasis and excessive endurance training stress (Noland et al., 2001; Lane et al., 2010). In competitive athletes, an increase in training volume has been associated with a reduction in energy intake and a loss of appetite (Budgett, 1990). "
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    ABSTRACT: This study was designed to determine endocrine responses during 2 days of strenuous resistance training. Ten healthy men performed resistance training twice a day for two successive days to induce acute fatigue (excessive physical stress). The resistance training consisted of four exercises for the lower body in the morning and seven exercises for the upper body in the afternoon. Maximal isometric and isokinetic strengths were measured from day 1 (before the training period) to day 3 (after the training period). Fasting blood samples were taken on days 1-3. Maximal isometric and isokinetic strengths significantly decreased with two successive days of training (P<0·05), with significant increases in serum creatine phosphokinase and myoglobin concentrations (P<0·05). Significant reductions in the fasting concentrations of serum insulin-like growth factor-1, free testosterone, insulin and high-molecular-weight adiponectin were observed on day 3 (P<0·05), whereas there were no changes in the serum cortisol concentration or the free testosterone/cortisol ratio. Plasma active ghrelin and serum leptin concentrations decreased by -20·7 ± 2·8% and -29·6 ± 4·1%, respectively (P<0·05). Two days strenuous resistance training significantly affects the profiles of anabolic hormone and endocrine regulators of appetite and energy balance, such as ghrelin and leptin. The present findings suggest that decreased ghrelin and leptin concentrations might reflect excessive physical stress and may be early signs of accumulated fatigue.
    Clinical Physiology and Functional Imaging 03/2013; 33(2):131-6. DOI:10.1111/cpf.12005 · 1.44 Impact Factor
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    • "The absence of an effect of an increase in training volume on leptin has also been described in swimmers over a training season [32]. However, they used rather intensive interval trainings [32] in contrast to lowintensity , high-volume training used in the studies where a decrease in leptin was found [17] [19] [44] [48]. This difference may also partly be due to the different energy systems that are stressed. "
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    ABSTRACT: The importance of physical exercise in regulating energy balance and ultimately body mass is widely recognized. There have been several investigative efforts in describing the regulation of the energy homeostasis. Important in this regulatory system is the existence of several peripheral signals that communicate the status of body energy stores to the hypothalamus including leptin, adiponectin, ghrelin, interleukin-6, interleukin-1β, and tumor necrosis factor-α--different cytokines and other peptides that affect energy homeostasis. In certain circumstances, all these peripheral signals may be used to reveal the condition of the athlete as the result of several months of prolonged exercise training. These hormone and cytokine concentrations characterize a physical stress condition in which different hormone and cytokine responses are apparently linked to changes in physical performance. The possibility to use these peripheral signals as markers of training stress (and possible overreaching/overtraining) in elite athletes should be considered. These measured hormone and cytokine levels could also be used to characterize the physical stress of single exercise session, as the hormone and cytokine response to exercise may actually be a response to the concurrent energy deficit. In summary, different peripheral signals of energy homeostasis may be sensitive to changes in specific training stress and may be useful for predicting the onset of possible overreaching/overtraining in athletes.
    Metabolism: clinical and experimental 03/2010; 60(3):335-50. DOI:10.1016/j.metabol.2010.02.009 · 3.89 Impact Factor
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