Resistance exercises

Resisted Exercises

1. RESISTANCE EXERCISES

2. Definitions: Resisted exercise: Resisted exercise is any form of active exercise in which dynamic or static muscle contraction is resisted by an outside force applied manually or mechanically.

3. Strength: Muscle strength is the greatest measurable force that can be exerted by a muscle or muscle group to overcome resistance during a single maximum effort. Power: Muscle power is defined as work produced by the muscle per unit of time. Power= force X distance/time Endurance: It is the ability to perform low intensity repetitive or sustained activities over a prolonged period of time.

4. Types of muscle works: Isometric muscle work: In this type of muscle work there is increase in tone of the muscle without any change in the muscle length. e.g. isometric strengthening for neck extensors: the clasped hand behind the head is pushed back by the head. No movement of the head or neck occurs but the tone of neck extensors increases.

5. Isotonic muscle work: in this type of muscle work there is change in length of the muscle while it maintains an even tone throughout the contraction period. This is of two types: Concentric work: here the origin and insertions come closer and the muscle length shortens. e.g. getting up from a chair: knee and hip extensors contract concentrically to bring about extension in these two joints. Eccentric work: here the origin and the insertion go away from each other and the muscle length increases. e.g. sitting on a chair from standing: knee and hip extensors contract eccentrically to bring about flexion in these two joints.

6. In concentric contraction the force generated by the muscle is greater than the resistance. In isometric contraction force generated by the muscle is equal to the resistance. In eccentric contraction the force generated by the muscle is lesser than the resistance.

7. Principles of resistance exercise Principle of overload : If muscle performance is to improve , a load that exceed the metabolic capacity of the muscle, must be applied; that is a muscle must be challenged to perform at a level greater than to which it is accustomed. Overload can be applied by increasing the intensity or volume. In strength training the intensity is increased where as in endurance training the volume i.e. frequency, repetitions and time is increased.

8. SAID (Specific Adaptation to Imposed Demand) principle: Adaptations produced by the training are highly specific to the nature of the stimulus or overload applied. SAID applies to all the systems of the body. The adaptations are specific to strength, power, endurance, functional activity, joint angle, sequence of muscle activations, energy systems and virtually all other variable present.

9. Principle of Reversibility: The adaptations achieved through resistance exercise persist as long as the resistance exercise is performed regularly and go back gradually to the pre exercise levels once the training is stopped. This means the effects of resistance training are reversible.

10. Inter individual variability: Every individual responds to resistance exercise in a different way, thus similar stimuli may bring about a lot of improvement in one patient and no improvement in others.

11. Ranges of muscle work FULL RANGE: Contraction takes place throughout the range, starting from fully stretched position in case of concentric contraction and from fully shortened position in case of eccentric contraction. Full range contractions are normally needed only during emergencies (e.g. preventing a fall). Uses: Maintain joint mobility Increase circulation Preparation for situations when power & mobility is needed.

12. Ranges of muscle work INNER RANGE: The muscle either shortens concentrically from half way of its range, or is lengthened by eccentric contraction from fully contracted state to halfway. Uses: Gain or maintain joint movement in the direction of muscle pull. Train some extensors that stabilize joints. E.g. Knee: VMO strengthening

13. Ranges of muscle work OUTER RANGE: Concentric contraction from fully stretched position to halfway range and eccentric contraction from halfway range to the fully contracted position Uses: Very useful for initiation of contraction (stretch reflex acts better) Muscles contract more forcefully (Frank sterling law)

14. Ranges of muscle work MIDDLE RANGE: In this range of muscle work the muscles neither reach the fully contracted range nor are fully stretched, but moves only in the range inbetween . This range is most functional and generally most efficient (angle of pull near 90 degree) USES: Maintenance of muscle tone and normal power .

15. Group action of muscles Prime movers/ agonists Antagonists Synergists Fixators

16. Indications Curative: Muscle: weakness or paralysis Bone: to increase density Aerobic system: improves aerobic capacity Other connective tissues: improve pliability and strength 2. Preventive : to preserve muscle power in all the conditions where muscle weakness is anticipated. To live a healthy life with high levels of fitness. 3. Preparative : to prepare for some specific activity where the adaptations of resistance exercise will be useful, e.g training for arm muscles of a boxer will prepare him for a better performance. 4 . Recreative : various form of resistance training is used as sports and recreation activity, like body building.

17. Adaptations of resistance exercise I. Neural adaptation: Starts within 4 weeks of regular training. Caused by decreased CNS inhibition, decreased GTO sensitivity & changes in NMJ Increased number of motor unit recruitment Increased rate of firing Synchronized firing

18. Adaptations of resistance exercise II. Skeletal muscle adaptation: A. HYPERTROPHY It is increase in the muscle bulk without increase in the number of muscle fibers, due to increased myofibril volume. Starts between 4-8 weeks of resistance training. Caused by increased protein synthesis and reduced protein degradation. Maximum hypertrophy in high volume moderate resistance exercises performed eccentrically.

19. Adaptations of resistance exercise B. HYPERPLASIA It means increase in the no. of muscle fibers. A small portion of muscle fibers may increase in number by longitudinal splitting. C. VASCULAR & METABOLIC ADAPTATIONS Increased capillary bed density Increased mitochondrial density ATP & CP storage increases Myoglobin storage increases CPK & Myokinase increases

20. Adaptations of resistance exercise III. Bone: Minimizes or prevents loss of bone mineral density. Can be used for the treatment of osteoporosis/ osteopenia IV. Connective tissue Tensile strength of tendons ligaments and connective tissue in muscle increases

21. DETERMINANTS OF RESISTANCE TRAINING Frequency Intensity Time Type Alignment & Stabilization Volume Periodization Rest interval Sequencing Integration to functional activities The determinants are interdependent for a successful regime

22. Repetition maximum RM is a method of quantifying exercise intensity, Given by Delorme Definition: A repetition maximum is defined as the greatest amount of weight a muscle can move through the available ROM for a specific no of times. 1 RM for a muscle is the maximum weight (resistance) with which the muscle can contract through full/ available ROM for one time. The muscle will be unable to perform the repetition for a second time . 10 RM for a muscle is the maximum weight (resistance) with which the muscle can contract through full/ available ROM for 10 times. The muscle will be unable to perform the 11 th repetition.

23. Uses of RM To document a baseline measurement of dynamic strength of a muscle To identify an exercise load to be used during exercise To find out prognosis in reassessment and alter the exercise regime accordingly.

24. How to measure 1RM? Measured by repetitions to fatigue method using equations/ charts. Various equations and charts are available eg . 1 RM=(No of reps/30)+1 X weight used Example: if one lifts 15 kg for 20 times, 1RM= ? For reps to fatigue the muscle is warmed up and stretched and then given a weight (preferably free weight) which can be performed comfortably over 5 repetitions. The no. of repetition the candidate can perform before fatigue is noted.

25. Training zone The amount of resistance to be used in a training program is usually a percentage of 1 RM For sedentary: 30-40% of 1 RM For untrained healthy individual: 60-70% of 1 RM For highly trained: 80-95% of 1 RM

26. Time/duration The duration of a resistance training regime is the total no. of weeks or months during which the exercise program is carried out. Duration determines the adaptations: < 4 weeks program-neural adaptation only. 6-12 weeks program- musculoskeletal adaptation (hypertrophy, increased vascularization )

27. Alignment and stabilization Alignment and stabilization is necessary for isolation of muscle and to prevent substitution. Stabilization can be external or internal by isometric contraction of a fixator , (e.g. abdominals in case of SLR)

28. Volume Volume is the summation of the total no. of repetitions and sets of a particular exercise during a single exercise session multiplied by the resistance used. Higher the intensity lower the no. of repetitions. Repetitions Repetitions is the no. of times a particular movement is repeated in a series of complete and continuous excursions against a specific load. Set A predetermined no. of repetitions grouped together is known as a set or bout. After each set there is a brief interval of rest.

29. Determination of repetitions: It is based on the principle of repetition maximum. Most commonly 10 repetitions of 10 RM is used. 10 RM is approximately 75% of 1RM. Alternatively 15 RM (60% of 1 RM) or 5 RM (90% of 1 RM) is used. A session may have a single set or multiple sets. Single set exercises are used with low intensity in early phases of rehab. For strength gaining multiple sets are recommended. For strength gain: low repetitions high resistance For endurance gain: high repetitions low resistance

30. Types of resistance Manual and mechanical Static and dynamic Concentric and eccentric Open and closed chain Constant and variable load Isokinetic exercise.

31. PRE Progressive resistance exercise is a dynamic resistance training in which a constant external load is applied to the contracting muscle by some mechanical means and incrementally increased. The RM is used as the basis of progression in the resistance. Multiple sets are used in a session, which may consist of 2-3 sets of 6-12 repititions of 6-12 RM Common variants are DeLorme , Oxford and McQueen method.

32. Delorme: 4 sessions weekly, progress 10 RM once weekly oxford: 5 times weekly

33. McQueen Regime : 10reps@ 100% of 10RM 10reps@ 100% of 10RM 10reps@ 100% of 10RM 10reps@ 100% of 10RM 3 sessions weekly. Progress 10 RM every 1-2 week

34. DAPRE

35. BRIME Gerber & Hicks described a program of brief isometric exercise of one to six isometric contractions, held for 3 to 6 secs , with 20 sec rests between contractions. Purpose is to maintain or slightly increase the strength of quadriceps during acute knee joint inflammation when the joint is otherwise held at rest and to avoid increasing blood pressure when this is a consideration. Usually done for arthritis.

36. Precaution Valsalva Substitution Overwork (weakness)/overtraining (fatigue) Muscle soreness: acute and DOMS Pathological fracture

37. Contraindication pain: Pain in free active movement Acute pain in resisted isometrics Pain that can not be eliminated by reducing the resistance 2. inflammation : Acute inflammation in muscle or inflammatory neuro muscular pathology Dynamic exercise is contraindicated in inflammation of the joint 3. Severe cardiopulmonary disease . 4. Loss of joint integrity