University of Iowa Children's Hospital, Iowa City, IA 52242, USA.
george-phillips@uiowa.edu
Glutamine is a popular dietary supplement consumed for purported ergogenic
benefits of increased strength, quicker recovery, decreased frequency of
respiratory infections, and prevention of overtraining. From a biochemical
standpoint, glutamine does play a physiologic role in each of these areas, but
it remains only one of a host of factors involved. This review examines the
effects of glutamine on exercise and demonstrates a lack of evidence for
definitive positive ergogenic benefits as a result of glutamine
supplementation.
Department of Physical Education and Sports Science, Democritus University of
Thrace, Komotini 69100, Greece.
Overtraining syndrome is characterized by declining performance and transient
inflammation following periods of severe training with major health
implications for the athletes. Currently, there is no single diagnostic marker
for overtraining. The present investigation examined the responses of
oxidative stress biomarkers to a resistance training protocol of progressively
increased and decreased volume/intensity. Twelve males (21.3+/-2.3 years)
participated in a 12-week resistance training consisting of five 3-week
periods (T1, 2 tones/week; T2, 8 tones/week; T3, 14 tones/week; T4, 2 tones/week),
followed by a 3-week period of complete rest. Blood/urine samples were
collected at baseline and 96 h following the last training session of each
period. Performance (strength, power, jumping ability) increased after T2 and
declined thereafter, indicating an overtraining response. Overtraining (T3)
induced sustained leukocytosis, an increase of urinary isoprostanes (7-fold),
TBARS (56%), protein carbonyls (73%), catalase (96%), glutathione peroxidase,
and oxidized glutathione (GSSG) (25%) and a decline of reduced glutathione (GSH)
(31%), GSH/GSSG (56%), and total antioxidant capacity. Isoprostanes and GSH/GSSG
were highly (r=0.764-0.911) correlated with performance drop and training
volume increase. In conclusion, overtraining induces a marked response of
oxidative stress biomarkers which, in some cases, was proportional to training
load, suggesting that they may serve as a tool for overtraining diagnosis.
Laboratório de Pesquisa do Exercício, Faculdade Social da Bahia, Av Oceânica
2717, Salvador, BA, Brazil.
Overreaching (OVR) is defined as the initial phase of overtraining syndrome
and is known as a metabolic imbalance leading to short-term fatigue. Exercise
increases reactive oxygen species production, which can oxidize intracellular
structures impairing cell function and thus leads to OVR process. The aim of
this work is to study the behavior of oxidative stress markers in subjects
submitted to an OVR protocol. Thirty rats were divided in exercise and control
group, and submitted to an 8-week-endurance training (ET) and a 3-week-OVR
protocol. Thiobarbituric acid reactive substances (TBARs), reactive
carbonylated derivatives (RCD), glutathione reductase (GR), catalase (CAT) and
citrate synthase (CS) activities and stress protein HSP72 were measured in
soleus (SO), extensor digital longus (EDL) and semitendinuous (ST) muscles. ET
induced significant enhancement (P<0.05) in CS, GR, CAT, TBARs, RCD and HSP72
in SO, EDL and ST. OVR induced higher levels (P<0.05) of TBARs, RCD and HSP72
compared with ET only in SO, while in EDL and ST all measured parameters
ranged at same levels reached during ET. We concluded that stress-induced OVR
protocol is fiber type dependent, the SO muscle fiber type I being the most
affected by this treatment.
PMID: 17346286 [PubMed - as supplied by publisher]
Peak Performance Project, Santa Barbara, California, USA.
The development of power lies at the foundation of all movement, especially
athletic performance. Unfortunately, training programmes of athletes often
seek to improve cardiovascular endurance through activities such as distance
training that are detrimental for the performance of power athletes, rather
than using other means of exercise. Performance decrements from continuous
aerobic training can be a result of inappropriate neuromuscular adaptations, a
catabolic hormonal profile, an increased risk for overtraining and an
ineffective motor learning environment. However, long, sustained exercise
continues to be employed at all levels of competition to obtain benefits that
could be achieved more effectively through other forms of conditioning. While
some advantageous effects of endurance training may occur, there are
unequivocal drawbacks to distance training in the power athlete. There are
many other types of conditioning that are more relevant to all anaerobic
sports and will also avoid the negative consequences associated with distance
training.
Center for Human Movement Sciences, University Medical Center Groningen,
University of Groningen, Groningen, The Netherlands. e.nederhof@rug.nl
Overtraining syndrome (OTS) is a major threat for performance and health in
athletes. OTS is caused by high levels of (sport-specific) stress in
combination with too little regeneration, which causes performance decrements,
fatigue and possibly other symptoms. Although there is general consensus about
the causes and consequences, many different terminologies have been used
interchangeably. The consequences of overreaching and overtraining are divided
into three categories: (i) functional overreaching (FO); (ii) non-functional
overreaching (NFO); and (iii) OTS. In FO, performance decrements and fatigue
are reversed within a pre-planned recovery period. FO has no negative
consequences for the athlete in the long term; it might even have positive
consequences. When performance does not improve and feelings of fatigue do not
disappear after the recovery period, overreaching has not been functional and
is thus called NFO. OTS only applies to the most severe cases. NFO and OTS
could be prevented using early markers, which should be objective, not
manipulable, applicable in training practice, not too demanding, affordable
and should be based on a sound theoretical framework. No such markers exist up
to today. It is proposed that psychomotor speed might be such a marker. OTS
shows similarities with chronic fatigue syndrome and with major depression (MD).
Through two meta-analyses, it is shown that psychomotor slowness is
consistently present in both syndromes. This leads to the hypothesis that
psychomotor speed is also reduced in athletes with OTS. Parallels between
commonly used models for NFO and OTS and a threshold theory support the idea
that psychomotor speed is impaired in athletes with NFO or OTS and could also
be used as an early marker to prevent NFO and/or OTS.
Laboratoire Biologie Interuniversitaire des Activités Physiques et Sportives,
Université Blaise Pascal de Clermont-Ferrand, Aubière, France. j.finaud@tiscali.fr
Free radicals are reactive compounds that are naturally produced in the human
body. They can exert positive effects (e.g. on the immune system) or negative
effects (e.g. lipids, proteins or DNA oxidation). To limit these harmful
effects, an organism requires complex protection - the antioxidant system.
This system consists of antioxidant enzymes (catalase, glutathione peroxidase,
superoxide dismutase) and non-enzymatic antioxidants (e.g. vitamin E [tocopherol],
vitamin A [retinol], vitamin C [ascorbic acid], glutathione and uric acid). An
imbalance between free radical production and antioxidant defence leads to an
oxidative stress state, which may be involved in aging processes and even in
some pathology (e.g. cancer and Parkinson's disease). Physical exercise also
increases oxidative stress and causes disruptions of the homeostasis. Training
can have positive or negative effects on oxidative stress depending on
training load, training specificity and the basal level of training. Moreover,
oxidative stress seems to be involved in muscular fatigue and may lead to
overtraining.
Departamento de Alimentos e Nutrição Experimental, Faculdade de Ciências
Farmacêuticas, Universidade de São Paulo, São Paulo, SP.
The overtraining syndrome is characterized by an excessive training that
results in several adverse effects the main of which being the decay in
performance. Its incidence among elite athletes has been experiencing a
significant increase lately, which prompted a rush of interest in the search
for efficient measures to prevent and treat this condition. It is necessary,
however, to clarify possible mechanisms involved in the development of
overtraining. Several hypothesis are being proposed, such as a greater
activation of both the autonomic nervous system and the
hypothalamic-pituitary-adrenal axis, and suppression of the
hypothalamic-pituitary-gonadal axis. On the contrary, some studies suggest
that the modulation of such systems is but a consequence of the overtraining
syndrome and not its cause. Thus, recent hypothesis related to cytokine
release, to central fatigue, to depletion of muscle and liver glycogen, and to
a reduction in glutamine availability during physical activity are being
raised.
General Medical Clinic, Departement of Clinical and Biological Sciences, San
Luigi Hospital, Orbassano, Turin, Italy.
Physical exercise is a type of allostatic load for several endocrine systems,
notably the hypothalamic-pituitary-adrenal (HPA) axis. Athletes undergoing a
strenuous training schedule can develop a significant decrease in performance
associated with systemic symptoms or signs: the overtraining syndrome (OTS).
This is a stress-related condition that consists of alteration of
physiological functions and adaptation to performance, impairment of
psychological processing, immunological dysfunction and biochemical
abnormalities. Universally agreed diagnostic criteria for OTS are lacking. The
pituitary-adrenal response to a standardized exercise test is usually reduced
in overtrained athletes. This HPA dysfunction could reflect the exhaustion
stage of Selye's general adaptation syndrome. The most attractive hypothesis
that accounts for the observed neuro-endocrine-immune dysregulation is the
Smith's cytokine hypothesis of OTS. It assumes that physical training can
produce muscle and skeletal trauma, thus generating a local inflammatory
reaction. With the excessive repetition of the training stimulus the local
inflammation can generate a systemic inflammatory response. The main actors of
these processes are the cytokines, polypeptides that modulate HPA function in
and outside the brain at nearly every level of activity. It is hoped that
future research will focus on endogenous risk factors for morbidities related
to the neuro-endocrine-immune adaptation to exercise.
Department of Exercise Science, University of Georgia, Athens, GA 30602, USA.
poconnor@coe.uga.edu
This brief review summarizes key epidemiological and experimental evidence
concerning relationships between chronic physical activity and feelings of
energy (vigor, vitality) and fatigue. The epidemiological studies show a
positive association between the amount of typical weekly physical activity
reported and the frequency with which people report feeling energetic. The
randomized controlled experiments show that 10-20 wk of exercise training is
associated with an increase in the frequency and intensity of feelings of
energy among fatigued people with medical conditions. The results of
longitudinal studies with non-fatigued, healthy adults are mixed. Overtraining
by athletes is associated with increased intensity of feelings of fatigue.
Additional well-controlled investigations into relationships between physical
activity and feelings of energy and fatigue, especially among sedentary and
fatigued individuals, are warranted given the available evidence and the
importance of these moods to health, work productivity, and quality of life.
Division of General Internal Medicine, University of Pittsburgh School of
Medicine, 5230 Centre Avenue, Pittsburgh, PA 15232, USA.
Exercise can have profound effects on numerous biologic systems within the
human body, including the central nervous system (CNS). The inherent
complexity of the CNS, and the methodologic difficulties in evaluating its in
vivo neurochemistry in humans, provide challenges to investigators studying
the impact of exercise on the CNS. As a result, our knowledge in this area of
exercise science remains relatively limited. However, advances in research
technology are allowing investigators to gain valuable insight into the
neurobiologic mechanisms that contribute to the bidirectional communication
that occurs between the periphery and the CNS during exercise. This article
examines how exercise-induced alterations in the CNS contribute to central
fatigue and the overtraining syndrome, and how exercise can influence
psychologic wellbeing and cognitive function.
Medicine & Science in Sports & Exercise. 30(7):1137-1139, July 1998. KUIPERS, HARM
Abstract:
Training and overtraining: an introduction. Med. Sci. Sports Exerc., Vol. 30,
No. 7, pp. 1137-1139, 1998. Elite sport requires high training volumes.
However, little is known about the relationship between training volume and
performance development. This relationship appears to have an inverted U-shape.
Short-term overtraining or overreaching is probably associated with
insufficient metabolic recovery, resulting in a decline in ATP levels.
Systemic overtraining or staleness is attributed to failure of the
hypothalamus to cope with the total amount of stress. Clinically, a
parasympathetic and sympathetic form has been distinguished. It is assumed
that these two forms express different stages of staleness. No specific,
simple, and reliable parameters are known to diagnose overreaching and
overtraining in the earliest stage.
Department of Human Movement Sciences and Education, University of Memphis,
Tennessee, USA. fry.andrew@cc.memphis.edu
Overtraining is defined as an increase in training volume and/or intensity of
exercise resulting in performance decrements. Recovery from this condition often
requires many weeks or months. A shorter or less severe variation of
overtraining is referred to as overreaching, which is easily recovered from in
just a few days. Many structured training programmes utilise phases of
overreaching to provide variety of the training stimulus. Much of the scientific
literature on overtraining is based on aerobic activities, despite the fact that
resistance exercise is a large component of many exercise programmes. Chronic
resistance exercise can result in differential responses to overtraining
depending on whether either training volume or training intensity is excessive.
The neuroendocrine system is a complex physiological entity that can influence
many other systems. Neuroendocrine responses to high volume resistance exercise
overtraining appear to be somewhat similar to overtraining for aerobic
activities. On the other hand, excessive resistance training intensity produces
a distinctly different neuroendocrine profile. As a result, some of the
neuroendocrine characteristics often suggested as markers of overtraining may
not be applicable to some overtraining scenarios. Further research will permit
elucidation of the interactions between the neuroendocrine system and other
physiological systems in the aetiology of performance decrements from
overtraining.
Does Overtraining Exist?: An Analysis of Overreaching and
Overtraining Research.
Review Article
Sports Medicine. 34(14):967-981, 2004. Halson, Shona L 1 2; Jeukendrup, Asker E 1
Abstract:
Athletes experience minor fatigue and acute reductions in performance as a
consequence of the normal training process. When the balance between training
stress and recovery is disproportionate, it is thought that overreaching and
possibly overtraining may develop. However, the majority of research that has
been conducted in this area has investigated overreached and not overtrained
athletes. Overreaching occurs as a result of intensified training and is often
considered a normal outcome for elite athletes due to the relatively short
time needed for recovery (approximately 2 weeks) and the possibility of a
supercompensatory effect. As the time needed to recover from the overtraining
syndrome is considered to be much longer (months to years), it may not be
appropriate to compare the two states. It is presently not possible to discern
acute fatigue and decreased performance experienced from isolated training
sessions, from the states of overreaching and overtraining. This is partially
the result of a lack of diagnostic tools, variability of results of research
studies, a lack of well controlled studies and individual responses to
training.
The general lack of research in the area in combination with very few well
controlled investigations means that it is very difficult to gain insight into
the incidence, markers and possible causes of overtraining. There is currently
no evidence aside from anecdotal information to suggest that overreaching
precedes overtraining and that symptoms of overtraining are more severe than
overreaching. It is indeed possible that the two states show different
defining characteristics and the overtraining continuum may be an
oversimplification. Critical analysis of relevant research suggests that
overreaching and overtraining investigations should be interpreted with
caution before recommendations for markers of overreaching and overtraining
can be proposed. Systematically controlled and monitored studies are needed to
determine if overtraining is distinguishable from overreaching, what the best
indicators of these states are and the underlying mechanisms that cause
fatigue and performance decrements. The available scientific and anecdotal
evidence supports the existence of the overtraining syndrome; however, more
research is required to state with certainty that the syndrome exists.
Medicine & Science in Sports & Exercise. 30(7):1146-1150, July 1998. SNYDER, ANN C.
Abstract:
Overtraining and glycogen depletion hypothesis. Med. Sci. Sports Exerc., Vol.
30, No. 7, pp. 1146-1150, 1998. Low muscle glycogen levels due to consecutive
days of extensive exercise have been shown to cause fatigue and thus
decrements in performance. Low muscle glycogen levels could also lead to
oxidation of the branched chain amino acids and central fatigue. Therefore,
the questions become, can low muscle glycogen not only lead to peripheral and
central fatigue but also to overtraining, and if so, can overtraining be
avoided by consuming sufficient quantities of carbohydrates? Research on
swimmers has shown that those who were nonresponsive to an increase in their
training load had low levels of muscle glycogen and consumed insufficient
energy and carbohydrates. However, cyclists who increased their training load
for 2 wk but also increased carbohydrate intake to maintain muscle glycogen
levels still met the criteria of over-reaching (short-term overtraining) and
might have met the criteria for overtraining had the subjects been followed
for a longer period of time. Thus, some other mechanism than reduced muscle
glycogen levels must be responsible for the development and occurrence of
overtraining.
R Budgett
British Olympic Medical Centre, Northwick Park Hospital,
Middlesex, United Kingdom.
The overtraining syndrome affects mainly endurance athletes. It is acondition of chronic fatigue, underperformance, and an increasedvulnerability to infection leading to recurrent infections. It is not yetknown exactly how the stress of hard training and competition leads to theobserved spectrum of symptoms. Psychological, endocrinogical,
physiological, and immunological factors all play a role in the failure torecover from exercise. Careful monitoring of athletes and their response
totraining may help to prevent the overtraining syndrome. With a
very carefulexercise regimen and regeneration strategies, symptoms
normally resolve in6-12 weeks but may continue much longer or recur
if athletes return to hardtraining too soon.
Title
Performance, Metabolic and
Hormonal Alterations during Overreaching
Author
Halson, Shona L.
Institution
Queensland University of
Technology
Date
2003
Abstract
Many athletes incorporate high
training volumes and limited recovery periods into their training regimes.
This may disrupt the fragile balance and the accumulation of exercise stress
may exceed an athlete’s finite capacity of resistance. A state of elevated
fatigue, increased mood disturbance and decreased exercise performance can
result. This is commonly known as overreaching and if increased training and
limited recovery is continued, it is believed that the more serious state of
overtraining may develop. This is relatively commonly experienced in
athletes, however little scientific investigation has been conducted to
determine the characteristics and underlying mechanisms. The overall aim of
this thesis was to gain a greater understanding of the state of overreaching
and to specifically provide new information on potential markers of this
state as well as possible mechanisms. To study the cumulative effects of
exercise stress and subsequent recovery on performance changes, fatigue
indicators and possible mechanisms, the training of endurance cyclists was
systematically controlled and monitored in two separate investigations. A
number of variables were assessed including performance, physiological,
biochemical, psychological, immunological and hormonal variables. In
addition heart rate variability and serotonergic responsiveness were also
assessed. Some of the more pertinent effects of overreaching included an
increase in heart rate variability, a reduction in carbohydrate oxidation,
an increase in serotonergic responsiveness and a reduction in stress hormone
concentrations. These results suggest that autonomic imbalance in
combination with decreased hormonal release appears to be related to the
decline in performance and elevated fatigue apparent in overreached athletes.
Additionally it also appears that alterations in the hypothalamic-pituitary
adrenal axis may occur in overreached athletes.
Title