Debunking Common Fitness Myths

Apr 30, 2024 | by Ellyn Johnson

In the ever-evolving world of health and fitness, myths and misconceptions can often circulate, clouding the path to achieving our health and wellness goals. With countless sources of information available in the digital era we live in, it’s easy to become overwhelmed and misled by well-intentioned advice or outdated beliefs. However, separating fact from fiction is crucial for anyone looking to embark on a journey towards improved fitness and well-being. In this article, we’ll dive deep into some common fitness myths, debunking common misconceptions that may be hindering your progress. Armed with evidence-based knowledge and a discerning eye, we’ll unravel the truth behind these myths, empowering you to make informed decisions and optimise your approach to fitness.

Myth 1: Delayed Onset Muscle Soreness (DOMS) is Caused by Lactic Acid Build-up

The myth surrounding Delayed-Onset Muscle Soreness (DOMS) often falsely attributes its cause to the accumulation of lactic acid in the muscles. This misconception suggests that during intense or unfamiliar exercise, the body produces lactic acid as a byproduct, which then builds up in the muscles, leading to soreness and discomfort. However, this interpretation of DOMS is inaccurate.

In reality, DOMS is believed to be caused by microscopic damage to muscle fibres, particularly during eccentric contractions, which involve lengthening of the muscle under tension. This damage triggers an inflammatory response in the body as it works to repair and rebuild the affected muscle tissue. This inflammatory response, along with other factors such as muscle fatigue and connective tissue damage, contributes to the sensation of soreness and stiffness typically experienced 24 to 72 hours after exercise.

While lactic acid does accumulate in the muscles during intense exercise, it is rapidly cleared from the bloodstream and metabolised by the body, during the activity itself and shortly after the activity ceases. Lactic acid buildup is not directly responsible for the delayed onset of muscle soreness experienced in the days following exercise. Thus, the notion that DOMS is solely caused by lactic acid accumulation is a common fitness myth that misinterprets the complex physiological processes involved in muscle repair and adaptation.

Myth 2: Cardio Burns More Fat Than Strength Training

While cardiovascular exercises like running or cycling “burn” calories during a workout and can have lasting effects shortly after exercise has ceased, strength training has a longer-lasting impact on metabolism. Just a reminder that ‘metabolism’ refers to the complex biochemical processes that occur within the body to maintain life. It involves the conversion of food (calories) into energy that the body can use to perform various functions, such as breathing, circulation, digestion, and cell repair – as well as running, jumping, squats, lunges and every other form of exercise! Building lean muscle mass through strength and resistance training increases the body’s resting metabolic rate, as muscle is metabolically active. This leads to more energy being “burned” throughout the day, even at rest. Having more muscle mass also helps us avoid weight gain in the long term. The more lean muscle tissue we have, the higher our resting metabolic rate over days, weeks, months and years. So while cardiovascular activity has numerous health and body composition benefits, resistance training has been shown to have a better impact on weight management in the long term. 

Myth 3: Lifting Weights Stunts Growth in Adolescents

This myth often discourages young people from participating in strength training for fear of stunting their growth. In reality, when performed using age-appropriate loading and with proper technique and supervision, strength training can be safe and beneficial for adolescents. It can help improve bone density, muscle strength, and overall physical fitness, as long as it’s appropriate for their age and developmental stage.

The 2014 Position Statement on Youth Resistance Training summarises the recent academic research regarding resistance training in young people. Here are some recent conclusions:

“Although the total elimination of sport-related and physical activity-related injuries is an unrealistic goal, multifaceted training programmes that include general and specific strength and conditioning activities may help to reduce the likelihood of injuries in youth.”
“Fears that resistance training would injure the growth plates of youths are not supported by scientific reports or clinical observations, which indicate that the mechanical stress placed on the developing growth plates from resistance exercise, or high strain eliciting sports such as gymnastics or weightlifting, may be beneficial for bone formation and growth.”
“Well-supervised, multifaceted resistance training programmes have been shown to reduce abnormal biomechanics (eg, increased knee valgus landing) that manifest during adolescence and appear to decrease injury rates in female athletes.”
“The available literature indicates that participation in the sport of weightlifting and the performance of weightlifting movements as part of a strength and conditioning programme can be safe, effective and enjoyable for children and adolescents provided qualified supervision and instruction are available and progression is based on the technical performance of eachlift. However, it must be emphasised that regardless of the exercise choice, all youth resistance training programmes should be consistent with a participant’s training age, technicalcompetency and maturational status.”

Extensive scientific evidence highlights the importance of engaging in properly structured youth resistance training programs under the guidance of qualified professionals. This position statement article builds upon existing position statements from medical and fitness organisations, highlighting the range of health, fitness, and performance advantages linked with such training for youngsters.

Myth 4: Muscle “Toning” Is Better For Women

The fitness goal of achieving a “toned” physique is common in the fitness industry. We hear phrases such as “muscle toning exercises” when describing particular movements or workouts. The issue here is that skeletal muscle tissue cannot “tone”. We can increase our lean muscle mass (we call this muscular hypertrophy), but muscle toning is simply not a physiological phenomenon. When we hear the phrase “muscle toning” it typically refers to the muscle definition visible beneath the skin. To achieve this type of physique or fitness outcome, what we’re actually after is an increase in lean muscle mass and a reduction in subcutaneous body fat. 

In addition to this perpetual myth floating around the industry, it’s often thought that this physique or fitness outcome is achieved through lifting lighter weights for higher repetitions. This type of training is great for improving muscular endurance but is less effective for building significant muscle mass or achieving noticeable definition. Instead, incorporating heavier resistance training with compound movements such as squats, deadlifts, and bench presses, alongside a balanced diet and cardiovascular exercise, is essential for sculpting a “toned” physique. This approach not only increases muscle mass but also boosts our resting metabolic rate, leading to greater fat loss and improved muscle definition. 

Myth 5: The New Fad of “Detox” Diets

Detox diets have gained popularity in recent years, often promoted as a quick fix to rid the body of toxins and jumpstart weight loss. These diets typically involve severe restrictions, such as consuming only juices, herbal teas, or specific food groups while eliminating others entirely. Advocates of detox diets claim that they help flush out toxins accumulated from processed foods, environmental pollutants, and other sources, thereby improving overall health and vitality. However, the premise of these diets is fundamentally flawed.

Our bodies are equipped with highly efficient detoxification systems, primarily the liver and kidneys, which work tirelessly to eliminate toxins and waste products from the body. The liver detoxifies the body by metabolising toxins and converting them into less harmful substances that can be excreted. It does this through a series of enzymatic reactions, breaking down toxins into water-soluble compounds that can be easily eliminated from the body via urine or bile. Meanwhile, the kidneys filter our blood, removing waste products and excess substances like urea, ammonia, and uric acid. These waste products are then excreted in the form of urine. Additionally, the kidneys help regulate electrolyte balance, blood pressure, and fluid levels in the body, further supporting overall detoxification.

Additionally, the lungs, skin, and lymphatic system also play crucial roles in the body’s natural detoxification processes. Therefore, the notion that we need to follow strict detox diets to cleanse our bodies of toxins is misleading. In fact, extreme detox regimens can be counterproductive and potentially harmful. Severely restricting calorie intake and eliminating essential nutrients can lead to nutrient deficiencies, weakened immune function, muscle loss, fatigue, and even organ damage in severe cases. Rapid weight loss from detox diets is often unsustainable and may result in the loss of water weight and muscle mass rather than fat loss, leading to a rebound effect once normal eating patterns resume. The bottom line? Leave the detoxing to our body’s organs and systems specifically designed by ‘Mother Nature’ to do just so.

In conclusion, navigating the landscape of health and fitness requires a critical eye and a commitment to separating fact from fiction. In a world inundated with information, it’s easy to fall prey to common myths and misconceptions that can hinder our progress toward our health and fitness goals. However, armed with evidence-based knowledge and a discerning mindset, we can debunk these myths and empower ourselves to make informed decisions about our health and fitness journey. Whether it’s understanding the true causes of delayed onset muscle soreness, recognising the long-term benefits of strength training, or debunking the myth of detox diets, we must rely on science and sound reasoning to optimise our approach to fitness. 


  • Cheung, K., Hume, P., & Maxwell, L. (2003). Delayed onset muscle soreness : treatment strategies and performance factors. Sports medicine (Auckland, N.Z.), 33(2), 145–164.
  • Lloyd, R. S., Faigenbaum, A. D., Stone, M. H., Oliver, J. L., Jeffreys, I., Moody, J. A., Brewer, C., Pierce, K. C., McCambridge, T. M., Howard, R., Herrington, L., Hainline, B., Micheli, L. J., Jaques, R., Kraemer, W. J., McBride, M. G., Best, T. M., Chu, D. A., Alvar, B. A., & Myer, G. D. (2014). Position statement on youth resistance training: the 2014 International Consensus. British journal of sports medicine, 48(7), 498–505.
  • Klein, A. V., & Kiat, H. (2015). Detox diets for toxin elimination and weight management: a critical review of the evidence. Journal of human nutrition and dietetics, 28(6), 675-686.
Ellyn Johnson

Ellyn Johnson

Ellyn is an Exercise Scientist specialising in youth Strength and Conditioning. She holds her Bachelor's degrees in Science and Exercise and Sports Science. She has previously worked as a Strength and Conditioning Coach for Academy level athletes at the Brisbane Lions Football Club. She has a background in Personal Training, coaching a range of clientele with diverse goals, including weight loss, body recomposition as well as recreational endurance athletes. In addition to her Strength and Conditioning experience, Ellyn currently works as a Learning Designer at the Australian Institute of Fitness. Here she works as a subject matter expert in the design and implementation of a range of health- and fitness-related courses and learning materials.

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