atleta

Perceived Exertion

 

ACSM current comment

Around the world in health clubs on the walls beside treadmills, stationary bikes and step machines, one often sees a scale going from 6-20. This is called an RPE Scale, which stands for “Rate of Perceived Exertion.” It is a psychophysiological scale, meaning it calls on the mind and body to rate one’s perception of effort. Understanding the meaning and use of this chart will benefit the average fitness enthusiast.

The RPE scale measures feelings of effort, strain, discomfort, and/or fatigue experienced during both aerobic and resistance training. One’s perception of physical exertion is a subjective assessment that incorporates information from the internal and external environment of the body. The greater the frequency of these signals, the more intense are the perceptions of physical exertion. In addition, response from muscles and joints helps to scale and calibrate central motor outflow commands. The resulting integration of feedforward-feedback pathways provides fine-tuning of the exertional responses.

Perceived exertion reflects the interaction between the mind and body. That is, this psychological parameter has been linked to many physiological events that occur during physical exercise. These physiological events can be divided into respiratory/metabolic (such as ventilation and oxygen uptake) and peripheral (such as cellular metabolism and energy substrate utilization.) Previous studies have demonstrated that an increase in ventilation, an increase in oxygen uptake, an increase metabolic acidosis or a decrease in muscle carbohydrate stores are associated with more intense perceptions of exertion. The scale is valid in that it generally evidences a linear relation with both heart rate and oxygen uptake during aerobic exercise.

How is perceived exertion measured? 

The level of perceived exertion is often measured with a 15 category scale that was developed by the Swedish psychologist Gunnar Borg. The Borg scale is shown below:

  • 6 No exertion at all
  • 7 Extremely light
  • 8
  • 9 Very light
  • 10
  • 11 Light
  • 12
  • 13 Somewhat hard
  • 14
  • 15 Hard (heavy)
  • 16
  • 19 Extremely hard
  • 20 Maximal Exertion

© Gunnar Borg 1985

The Borg scale is simple to understand and very user-friendly. However, to use it effectively, it is necessary to adhere to the standard guidelines in measuring perceived exertion. These guidelines are:

1) It should be clear to either the client, patient, or athlete that perceived exertion is a method to determine the intensity of effort, strain, and/or discomfort that is felt during exercise;

2) The range of sensations must correspond to the scale. For example, number 6 should be made in reference to the feelings during rest, whereas number 20 should refer to the maximal level of exertion;

3) Either the RPE should be made specific to the overall body perception or the perception derived from a certain anatomical region of the body such as chest, arms and/or legs. Typically, individuals interested in monitoring the stress of a workout use RPE ratings.

4) It is important to know that when rating one’s perception of exertion there is no right or wrong

answer for the rating. However, the individual must clearly understand the meaning of the descriptors, so careful explanation of the scale is necessary before using.

How can ratings of perceived exertion be used? 

Due to its reasonably linear relation with oxygen uptake and heart rate, RPE can be used to guide the progression of a graded exercise test. This is accomplished by providing subjective confirmation that end-points of the test have been achieved once the terminal rating is reported or by signaling the relative metabolic stress at a given time during the test. Based upon the fact that RPE’s positively correlate to power output over a wide range of intensities, they can also be used to predict aerobic power in a manner analogous to the way that heart rate is employed in submaximal testing.

Ratings of perceived exertion can also be used to prescribe and monitor exercise intensity during a workout. A common approach is to periodically ask a person to rate his or her perceived exertion for a given exercise intensity during a stress test and then match it to an appropriate exercise intensity prescription. Attempting to keep the RPE within a training range similar to heart rate training ranges can be effective. Using this procedure, the target RPE ratings are based upon prior test results, and the person is requested to produce intensity perceived to be similar to the target rating during a workout. The key is close approximation to heart rate in aerobic exercise, where the RPE scale is most often used.

A question is sometimes raised as to whether the intensity produced based on perceptual ratings is actually what it is supposed to be. Several recent studies have attempted to answer this question. These studies have used oxygen uptake as an objective variable and found no difference between the oxygen uptake that was estimated from the prior test results and oxygen uptake that was produced during a subsequent workout. This finding suggests that using a “target RPE” as a guide to regulate exercise intensity is valid.

It is important to note that using the RPE can be especially important in two situations. If heart-rate measurement is difficult for some reason, or if the individual is on medication that alters normal heart rate response to physical stress, RPE can be an excellent tool to regulate and monitor intensity. The RPE scale continues to be a useful tool, offering subjective reflection of physiological responses during physical exercise, and enabling the individual to regulate effort to gain maximum benefit.

 

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Ankle Sprains and the Athlete

ACSM current comment

Summary

Ankle sprains are one of the most common injuries in the athlete. Accurate and rapid diagnosis, comprehensive treatment, and rehabilitation are critical in reducing the risk of re-injury or chronic disabling ankle pain. Prevention of injury should be a part of any training and exercise plan. The ultimate goal of any treatment program is to improve function without inhibiting the athlete’s performance

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 Reports estimate that 25,000 Americans suffer from an ankle sprain each day. Ankle sprains account for almost half of all sports injuries and are a common reason why athletes take time off from activities. Accurate diagnosis is critical, as some studies suggest that 40 percent of ankle sprains are misdiagnosed or poorly treated leading to chronic ankle pain and disability. Self-education is therefore important in order to decrease the risk of this disabling complication.

What is an ankle sprain?

An ankle sprain is an injury to one or more of the ligaments in the ankle. These strong fibrous bands hold together the bones of the ankle and are prone to injury during strenuous movement and repetitive activity. There are two categories of ankle ligaments: those on the outer and those on the inner surfaces of the ankle. The most common sites of injury are in the outer – or “lateral” – ankle ligaments.

Common Causes

More than 80 percent of ankle sprains are a result of inversion, or inward rolling, of the ankle. This is commonly experienced in athletic activities that involve running, pivoting and jumping. While sudden, forceful movements are certainly the cause of many ankle sprains, low-grade repetitive trauma can also weaken and injure ankle ligaments. Risk factors for ankle sprains include previous ankle injury, impaired balance/postural control, type of sport played, position, and muscle strength/range-of-motion deficits. Excess body weight may also be a risk factor for males.

Evaluation and Diagnosis

Obtaining a thorough, detailed history of events is critical in the evaluation of ankle pain in order to lead to an accurate diagnosis. Immediate evaluation is important to determine if there are any other injuries such as a fracture. Common signs and symptoms of an ankle sprain include swelling, pain, instability and bruising. Numbness or severe weakness may suggest a related nerve injury. Examination of the ankle for evidence of instability and localizing pain is part of the initial assessment. Clinicians may often obtain x-rays or MRIs for further evaluation. A widely validated and sensitive rule of the thumb for assessing ankle sprains is known as the Ottawa Ankle Rules. These rules recommend imaging for possible fracture if there is pain on the side of the ankle with palpation and the patient is unable to walk four steps without pain. Ankle sprains are generally categorized into three grades:

Grade I : The most common type; these are associated with a mild degree of swelling and pain related to stretching of the ligament.

Grade II : More commonly seen in athletic injuries, these are associated with a moderate degree of swelling and pain and are related to an incomplete tear of the ligaments.

Grade III : The most severe of ankle sprains; these are associated with significant swelling and pain and are related to complete tear of the ligaments.

Initial Treatment and Prognosis

After an accurate diagnosis is obtained, treatment will vary depending on the severity of injury. Early and comprehensive treatment remains the best predictor of a good recovery. Initial treatment includes four common concepts referred to as R.I.C.E. (Rest, Ice, Compression, and Elevation). Relative rest or discontinuation of athletics is often necessary. Ice bags applied at 20-minute intervals three times per day for at least 72 hours post injury, along with compression and elevation, can help reduce swelling and pain. A thorough evaluation by a medical expert will help determine other possible treatments, including bracing, taping and anti-inflammatory medications.

Prognosis is directly related to the severity of injury. Immediate evaluation and treatment will often lead to an increased chance of complete recovery. Surgery is rarely necessary, as most ankle sprains will heal with conservative management.

Rehabilitation

A comprehensive rehabilitation program is a critical part in the treatment of ankle sprains. With the guidance of an experienced physical therapist or athletic trainer, stretching and strengthening of the ankle joint and calf muscles will quicken the recovery time and decrease the risk of re-injury. To maintain cardiorespiratory fitness during recovery,walking or jogging in a pool or cycling is recommended, as the weight on the ankle is decreased. Re-training the muscle sensation (called proprioception) and postural control (balance) should be a critical component of any rehabilitation program. Balance training, using ‘wobble boards’, is an excellent rehabilitation technique that helps strengthen and stabilize the ankle, reducing the risk of re-injury. Returning to activities usually varies from a few days to two months, depending on the severity of injury.

Prevention of Re-Injury

Prevention in athletics is an important matter to discuss with a skilled sports medicine practitioner. Properly applied external ankle supports (tape, semi-rigid, and rigid braces) and balance board exercise training can reduce the risk of ankle re-injury by more than 50%. These prevention strategies are especially effective for those with a history of a previous ankle injury. External ankle supports do not adversely affect athletic performance. Semi-rigid and rigid ankle supports are most effective, widely available, and cost less than athletic tape.

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Nutrition and Athletic Performance

Joint Position Statement: American Dietetic Association, Dietitians of Canada, and the American College of Sports Medicine

ABSTRACT

It is the position of the American Dietetic Association, Dietitians of Canada, and the American College of Sports Medicine that physical activity, athletic performance, and recovery from exercise are enhanced by optimal nutrition. These organizations recommend appropriate selection of foods and fluids, timing of intake, and supplement choices for optimal health and exercise performance.

This updated position paper couples a rigorous, systematic, evidence-based analysis of nutrition and performance-specific literature with current scientific data related to energy needs, assessment of body composition, strategies for weight change, nutrient and fluid needs, special nutrient needs during training and competition, the use of supplements and ergogenic aids, nutrition recommendations for vegetarian athletes, and the roles and responsibilities of the sports dietitian.

Energy and macronutrient needs, especially carbohydrate and protein, must be met during times of high physical activity to maintain body weight, replenish glycogen stores, and provide adequate protein to build and repair tissue. Fat intake should be sufficient to provide the essential fatty acids and fat-soluble vitamins and to contribute energy for weight maintenance. Although exercise performance can be affected by body weight and composition, these physical measures should not be a criterion for sports performance and daily weigh-ins are discouraged.

Adequate food and fluid should be consumed before, during, and after exercise to help maintain blood glucose concentration during exercise,maximize exercise performance, and improve recovery time. Athletes should be well hydrated before exercise and drink enough fluid during and after exercise to balance fluid losses. Sports beverages containing carbohydrates and electrolytes may be consumed before, during, and after exercise to help maintain blood glucose concentration, provide fuel for muscles, and decrease risk of dehydration and hyponatremia.

Vitamin and mineral supplements are not needed if adequate energy to maintain body weight is consumed from a variety of foods. However, athletes who restrict energy intake, use severe weight-loss practices, eliminate one or more food groups from their diet, or consume unbalanced diets with low micronutrient density may require supplements. Because regulations specific to nutritional ergogenic aids are poorly enforced, they should be used with caution and only after careful product evaluation for safety, efficacy, potency, and legality.

A qualified sports dietitian and, in particular, the Board Certified Specialist in Sports Dietetics in the United States, should provide individualized nutrition direction and advice after a comprehensive nutrition assessment.

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Alcohol and Athletic Performance

ACSM current comment

The effects of alcohol can depend on the amount consumed, the environmental context, and on the individual. Daily consumption of up to four drinks may have a protective effect on the cardiovascular system. Nonetheless, people most commonly drink for alcohol’s anxiolytic (stress-reducing) property. Conversely, alcohol has a wide spectrum of negative effects, from societal to physiological, accounting for approximately 100,000 deaths yearly in the United States. From a physiological perspective, two situations draw special attention for the fitness-oriented individual who consumes alcohol. Acutely, alcohol can cause negative effects on motor skills and physical performance. Chronically, alcohol abuse may eventually impede physical performance; individuals diagnosed with alcohol dependence have displayed varying degrees of muscle damage and weakness. Furthermore, alcohol abuse is at least as prevalent in the athletic community as it is in the general population; the vast majority of athletes have begun drinking by the end of high school.

ALCOHOL USE IN ATHLETICS 

Alcohol use by athletes often starts at the junior high school level and can start even earlier. Among high school students, male athletes are more likely to not only use alcohol regularly but also to abuse alcohol. This relationship does not seem to exist at the college level. Nonetheless, alcohol consumption is high enough for alcohol to have been named the most abused drug in collegiate sport by the NCAA and in professional and Olympic sports by the NFL, NBA, and USOC.

ALCOHOL AS A NUTRIENT 

Each gram of alcohol (ethanol) provides seven kilocalories compared to nine for fat and four each for carbohydrate and protein. Other nutrients may be present, depending on the type of beverage. Beer, for example, has been seen as a good source of many nutrients and has sometimes been used in preparation for endurance events or to replenish nutrients following competition. Actually, orange juice supplies four times the potassium plus almost three times the carbohydrates, and it would take 11 beers, for example, to obtain the B-vitamin recommended daily allowance (RDA).

PERFORMANCE WHILE BLOOD ALCOHOL IS PRESENT (ACUTE EFFECT) 

Motor Performance – Low amounts of alcohol (0.02-0.05g/dL) can result in decreased hand tremors, improved balance and throwing accuracy, and a clearer release in archery, but in slower reaction time and decreased eye-hand coordination. A moderate (0.06-0.10 g/dL) amount of alcohol negatively affects such skills.

Strength/Power and Short-term Performances – The effect of alcohol, in low to moderate doses, is equivocal. It can have a deleterious effect on grip strength, jump height, 200- and 400-meter run performance, and can result in faster fatigue during high-intensity exercise. Conversely, alcohol has been shown to lack an effect on strength in various muscle groups, on muscular endurance, and on 100-meter run time.

Aerobic Performance – Low or moderate amounts of alcohol can impair 800- and 1500-meter run times. Because of its diuretic property, it can also result in dehydration, being especially detrimental in both performance and health during prolonged exercise in hot environments.

PERFORMANCE DURING HANGOVER 

Any lingering effect of alcohol would especially hinder physical conditioning progress. According to current research, the effect during a hangover seems to be undecided, with no effect on several performance variables, but a decline in total work output during high-intensity cycling. Furthermore, handgrip muscular endurance has been shown to suffer a delayed decline on the second morning following intoxication.

PERFORMANCE WITH CHRONIC ALCOHOL USE 

Chronic alcohol abuse may be detrimental to athletic performance secondarily to many of the sequelae that can develop. Alcohol affects the body’s every system, linking it to several pathologies, including liver cirrhosis, ulcers, heart disease, diabetes, myopathy, bone disorders, and mental disorders. The following implications may especially interest the athletic individual. Alcohol can result in nutritional deficiencies from alterations in nutrient intake, digestion, absorption, metabolism, physiological effects, turnover, and excretion of nutrients. Myopathy (muscle damage, wasting, and weakness) can occur in various muscles, including the heart, often compounded by alcohol-caused neuropathies. Also, the hormonal environment can change, making it less conducive to increasing muscle mass and strength.

PRACTICAL APPLICATIONS 

There are various methods to screen for alcohol abuse. Standardized questionnaires are available, but taking a more subtle approach by adding questions in medical history forms may be more effective. A team physician may also look for certain signs in the athlete’s appearance, but this has limited usefulness; it is good only for extreme cases of alcoholism. Athletes should be informed of all of alcohol’s detrimental aspects. Team rules and guidelines such as the following can be used:

* Pre-event: Avoid alcohol beyond low-amount social drinking for 48 hours.

* Post-exercise: Rehydrate first and consume food to retard any alcohol absorption.

To address any underlying causes of alcohol abuse, professional counseling should be available to athletes either directly or by referring athletes to community resources.

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blog | A propósito de “LANCE”

 

Más allá de la evidencia sobre el uso o abuso de sustancias prohibidas, el caso de Lance Armstrong, sin duda el mejor ciclista de ruta de todos los tiempos, ilustra la complejidad del deporte competitivo.

En muchos casos se juzga con severidad al atleta, quien frecuentemente es el eslabón final de una cadena de presiones económicas, sociales y políticas por alcanzar el triunfo a cualquier costo.

A diferencia de muchas decisiones importantes en salud, la mayoría de los deportistas no tiene la información completa y objetiva sobre las ventajas y riesgos de cada una de las recomendaciones médicas , técnicas y nutricionales que recibe de sus superiores. Más aún, la subordinación a dirigentes deportivos y patrocinadores los obliga con frecuencia a seguir rigurosamente las órdenes de sus entrenadores, médicos y directivos, quienes tienen como misión fundamental garantizar el triunfo y la figuración del atleta, de su equipo, marca, gremio, región o país.

Este entorno poco tiene de ético o de preocupación genuina y honesta por respetar el juego limpio o la salud del ser humano y pone a los grandes atletas en situaciones de poca libertad a la hora de tomar una decisión informada sobre las numerosas opciones técnicas, médicas y nutricionales que hacen parte del mundo competitivo.

La frustrante lucha contra el dopaje es un reflejo más de la incoherencia de una sociedad que aplaude únicamente el triunfo, la medalla o el título, que solo pueden alcanzar unos pocos entre miles de atletas de condiciones admirables y desconoce casi por completo la lucha heroica de niños y adolescentes por buscar un futuro mejor para ellos y sus familias. Que “lance” la primera piedra quien haya respetado todas las normas éticas y morales ante la promesa del éxito o la amenaza del fracaso…

Como en otros fenómenos preocupantes de nuestra sociedad moderna, si realmente queremos un cambio, debemos cuestionarnos a cerca de las raíces y responsables reales del problema y no pretender solucionarlo exclusivamente por medio de reglamentos, normas y sanciones, que aunque necesarias, son claramente insuficientes.

- JD