Concentric exercise is the most popular type of muscle contractions and it is the upwards motion of the major lifts. Basically, the muscle/s shortens to act against the resistance or weight. For example, during the hamstring curl, the hamstring temporarily shortens during the lifting phase and it also tenses up. No type of resistance training is absolutely perfect, but concentric training does have its fair share of benefits attached to it!
Why Is Concentric Contraction Important?
Concentric training is important because it can be bolted on to many principles of progressive resistance training. When lifting heavy weights using a medium rep range (4-8) and set number (1-3), you will increase the size of your muscle mass at a steady rate. Concentric exercises are a ‘fairly’ essential catalyst for your muscles to grow and develop. Therefore, ‘possibly’ the biggest benefit of concentric exercise is that that it does increase the overall size of your muscles.
What does the research say?
Research has indicated that concentric training can increase your muscle size by 4% and strength by 40% after an 8 week training program (1) Concentric exercises provide an effective stimulus for muscle growth while causing minimal stress to the post exercise recovery process (2). Concentric exercises do increase the anabolic hormones which is excellent news for muscle growth and repair. In addition, they don’t significantly induce muscular damage and only slightly impair your neuromuscular function. A dampened neuromusclar function has strong links with muscle soreness post exercise.
Musculoskeletal Health Benefits of Concentric Resistance Training
1. Protects Against Sarcopenia
Sarcopenia is a clinical condition described as a state of chronic muscle loss and strength reduction. Sarcopenia is associated with restricted function, disability, lack of independence, social isolation, and death. Resistance exercise has been shown to counteract sarcopenia by promoting muscle growth, increasing strength, and improving idependent function.
Spanish researchers reviewed the effectiveness of progressive resistance training. A total of 147 studies were found which resistance exercise performed by sessions 45-60 minutes, 2-3 times a week, and 3-4 sets of 8 repetitions, to an increasing intensity. This exercise resulted in increased muscle mass and strength, and increased skeletal muscle protein synthesis and muscle fiber size. (Palop Montoro MV et al. (Sarcopenia intervention with progressive resistance training and protein nutritional supplements. Nutr Hosp. 2015 Apr 1;31(4):1481-90.)
2. Promotes New Bone Growth
During resistance training the force generated at the area where muscle attaches to bone induces a pro bone growth stimulus that promotes new bone formation. This mechanism helps bone resist the stresses created at the bone-muscle interface. Additionally, adjacent areas experience an increase in bone mineral density, and a decrease bone resorption .
Researchers from Maryland reviewed the effect of weighted exercises on bone mineral density in post menopausal women. The authors concluded a resistance training program of moderate to high intensity (70 to 90% of one maximum repetition-1RM), including 3 to 4 bouts of 8 to 12 repetitions of each exercise, performed 2 or 3 times a week, is able to maintain or improve the BMD of hip and femur in postmenopausal women when performed over one year duration (Zehnacker CH et al. Effect of weighted exercises on bone mineral density in post menopausal women. A systematic review. J Geriatr Phys Ther. 2007;30(2):79-88.)
3. Counteracts Symptoms of Osteoarthritis
Muscle strengthening through resistance exercise increases physical function, decreases pain and reduces self-reported disability. Resistance training helps correct abnormal muscle firing patterns that contribute to joint deterioration, promotes the release of natural pain killers, and reduces local low grade inflammation.
Turkish researchers in Florida examined the effects of concentric resistance training on functional capacity and symptoms in patients with osteoarthrosis of the knee. The investigators found concentric training showed marked decreases in pain scores, increased functional capacity, and increased cross sectional areas of knee muscles. (Gür H et al. Concentric versus combined concentric-eccentric isokinetic training: effects on functional capacity and symptoms in patients with osteoarthrosis of the knee. Arch Phys Med Rehabil. 2002 Mar;83(3):308-16.)
4. Decreases Belly Fat
Belly fat is an important risk factor for low grade inflammation. Low grade inflammation is associated with chronic musculoskeletal diseases such as osteoarthritis, osteoporosis, and sarcopenia(muscle loss). Additionally, unwanted belly fat overloads lower extremity joints accelerating their degeneration.
Researchers at TCU examined the influence of moderate- to high-intensity resistance training on inflammatory markers in elderly women. The investigators concluded that hat 10 wk of moderate- to high-intensity resistance training reduced the systemic inflammatory milieu. (Phillips MD et al. Resistance training at eight repetition maximum reduces the inflammatory milieu in elderlywomen. Med Sci Sports Exerc. 2010 Feb;42(2):314-25. )
5. Promotes Healthy Blood Sugar Levels
Skeletal muscle is the primary site for glucose storage. Resistance training improves muscle uptake and storage of glucose. In the absence of adequate glucose muscle storage, excessive free sugar reacts with vital structures in joints and bones altering their structure and biomechanical properties. This leads to premature aging and dysfunction.
Australian investigators systematically reviewed the effect of resistance training on glycemic control and insulin sensitivity in adults with type 2 diabetes. The researchers reported clinically relevant reductions in glycosylated haemoglobin, a marker of blood glucose control. (Gordon BA et al. Resistance training improves metabolic health in type 2 diabetes: a systematic review. Diabetes Res Clin Pract. 2009 Feb;83(2):157-75. )
6. Boosts Mitochondrial Health
Mitochondria are the power generates of the cell and play a key role in cell vitality. Mitochondrial dysfunction has been linked to multiple chronic musculoskeletal diseases including: osteoporosis, osteoarthritis, and sarcopenia. Research suggests resistance exercise has the power to improve mitochondrial function and stimulate mitochondrial production.
Researchers in Florida examined the influence of resistance training on markers of mitochondrial health. The investigators found resistance increased mitochondrial content and enzyme activity. (Sparks LM et al. Nine months of combined training improves ex vivo skeletal muscle metabolism in individuals with type 2 diabetes. J Clin Endocrinol Metab. 2013 Apr;98(4):1694-702.)
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