1. Mosso’s Ergography Dr. Ravi Dutt (MBBS, MD) Senior Resident Department of physiology MAMC, Delhi *with video explaining the apparatus and procedure

2. Student’s Objective After completing the practical, the students should be able to : 1.Define Ergography. 2.Explain the physiological significance of this practical. 3.Calculate the work done using Mosso’s ergograph. 4.Enlist the factors affecting fatigue and work done. 5.Explain the effect of Venous and arterial occlusion on work done.

3. AIM To study the phenomenon of human fatigue and to calculate the work done using Mosso’s ergograph. To study the effect of arterial and venous occlusion on the onset of fatigue by using Mosso’s ergograph

4. Introduction Mosso’s ergography is done to record the voluntary isotonic contractions of a skeletal muscle. The erg is the unit of work and ergograph is the apparatus used for recording voluntary contractions of skeletal muscle in humans. The Mosso’s ergograph is employed not only to assess the performance of hand and forearm muscles but also to study the phenomenon of fatigue and the factors that affect fatigue.

5. APPARATUS Mosso’s Ergograph Meteronome Kymograph Paper, Pen marker and Ink Weights Sphygmomanometer

6. Principle Concept of Human Fatigue: Fatigue is defined as a temporary and reversible loss of the physiological property of contraction of skeletal muscles. Fatigue may be subjective i.e. feeling of a sensation of tiredness or objective i.e. measurable decrement in performance. These two phenomenon's are dependent on each other. The development of fatigue in voluntary contacting muscles can be shown by lifting a weight in Mosso’s ergograph.

7. Mosso’s Ergograph

8. It consists of a flat wooden board with 2 pairs of clamps and curved plates to fix, hold, and steady the forearm of the subject. There is a pair of metal tubes (finger holders) for fixing index and ring fingers in position. The middle finger remains free to be connected to a thick cord and hook. A hook (for suspending weights) is attached to a cord, is made to hang over the pulley. The other end of the cord is attached to a sliding plate which moves to and fro. A sliding plate carries a lever system to record muscle exertions on a kymograph cylinder. The other end of the plate is connected through a sling to the middle finger of the hand. Alternatively the sliding plate can carry a chart paper on which a pencil or ballpoint pen can record the contractions

9. Mosso’s Ergograph video description

10. Meteronome It is a timing device which functions as a variable interrupter to deliver the sounds at a preselected frequency. For this experiment, the sound frequency is to be set at 30 beats/min

11. Procedure The Mosso’s ergograph is set on a table of suitable height. Explain the procedure to the subject and seat her/him beside the table. Fix the forearm on the ergograph, and insert the index and ring fingers in the finger holders and ensure movement of only middle finger. Put a suitable weight usually of 2 kg on the weight stand and place the kymograpgh with paper such that the movements of sliding plate can be recorded on it. Keep the speed of kymograph drum at 2.5 mm /sec. Adjust the beat of the metronome at 30/minute, i.e. one beat every 2 seconds, and set it oscillating. Put the middle finger in the hook and ask the subject to pull the cord by flexing the middle finger maximally and rhythmically, following each beat of the metronome. continue the procedure until fatigue is so great that the weight can no longer be lifted. Label the graph with weight with which it was done. After a rest of 15 min, repeat the procedure with increased weight(2.5 and 3kg) following the same steps.

12. Video of Mosso’s Ergography Procedure

13. Effect of venous and arterial occlusion Effect of venous occlusion. After a rest of 15 min, apply the BP cuff on the upper arm and raise the pressure to 40 mm Hg to stop venous return. Repeat the whole procedure as before. Fatigue sets in earlier because of accumulation of waste products in the exercising muscles. Effect of arterial occlusion. After another period of rest of 15 min, raise the pressure of the cuff till the disappearance of radial pulse (130-140 mm Hg) to stop arterial and venous occlusion. Tell the subject to repeat the procedure. Fatigue sets in much earlier now because there is not only an accumulation of waste products but also a deficiency of oxygen and other nutrients.

14. CALCULATIONS The work done (W) in each of the above cases may be calculated by the below formula: W= F x D W= work done( in kg meters) F= weight lifted (in kg) D= total distance moved (in meters) To get the total distance (D) moved, measure the total length of all vertical lines.

15. Alternatively, D= No. of contractions x average height of contractions(A) where Area of triangle[1/2 base(b) x height(h)] + area of reactangle [length(a) x breadth(h)] A= ___________________________________ Total lenghth of base (a +b)

16. Calculation of onset of fatigue (in Min.) For this, Measure the total horizontal distance moved till the onset of fatigue and labeled it as X in each case. As the speed of the drum is 2.5 mm/sec, so 2.5 mm distance is covered in ------------ 1 sec 1 mm distance is covered in --------------- 1 / 2.5 sec So, X distance is covered in ----------------- 1 /2.5 * X sec

17. Result Table S. NO.WEIGHT (IN kg)Metronome frequency Work done (in kgm)Fatigue time in Min 1.230/min 2.2.530/min 3.330/min Effect of venous and arterial occlusion on onset of fatigue Effect of increasing weight on onset of fatigue and work done S. No.CirculationMetronome Frequency Weight constant (kg) Onset of fatigue in Min 1.30/min 2.30/min 3.30/min

18. Physiological significance The degree, duration and type of work done are the important factors that affect the onset of fatigue. Onset of Fatigue depends on: The weight to be lifted Frequency of contractions Motivation Blood supply to contracting muscles Training Environmental factors such as temperature and humidity

19. The fatigue developing in maximal voluntary muscular efforts, first occurs in Central nervous system, followed by Neuromuscular junction and lastly in muscle proper. The performance of a person can be increased by encouragement and motivation. This shows that fatigue has a cortical component. Venous occlusion decreases the work done due to accumulation of metabolites in the muscle. Arterial occlusion further decreases the work done and brings in an early onset of fatigue as it prevents the supply of nutrients to the muscle.

20. References Ghai’s Text book of Practical Physiology (9 th edition) Revised & edited by Dr. V.P. Varshney and Dr. Mona Bedi Essentials of MD/DNB Physiology Practical Examination by Dr. A.K. Jain Comprehensive Text book of Physiology by Dr. G.K.Pal

21. Thank You