Cause of Weakness 2
IDENTIFY – The cause of my weakness, early fatigue during the final quarter of a netball match, is due to me having poor stamina.
EXPLAIN – Stamina (cardio respiratory endurance) is the ability to provide and sustain energy aerobically. It is dependant on the ability of the cardiovascular system to transport and utilise oxygen during sustained exercise. Cardio respiratory endurance helps in netball when the performer need to withstand fatigue, recover during periods of less intense activity and so last the duration of the game. Hence, having poor stamina causes my muscles and mind to fatigue quicker, this would result in poor technique and incorrect strategic decisions. The early fatigue is due to a lack of training in the aerobic training zone (approx. 60%-80% of maximum heart rate). During a game of netball the main energy systems used; the lactic and aerobic systems. The lactic system is the main system used when moving a dodging a player at a turn over (approx. 60 seconds) and the aerobic system is predominantly used for the continuous movement throughout the game (60 minutes) and during recovery (EPOC). Both systems resynthesise ATP (Adenosine Tri-Phosphate). As it is stamina that is my weakness it is the aerobic system that I need to work at improving in order to increase my aerobic energy stores of muscle glycogen, triglycerides and myoglobin. It also improves the mitochondria and enzyme capacity. The aerobic system is defined as; GLUCOSE (C6H12O6) + OXYGEN (6O2) CARBON DIOXIDE (CO2) + WATER (O2) + ENERGY (38ATP).
The aerobic system goes through 3 stages. The first stage, aerobic glycolysis in the sarcoplasm, glycogen and fats are converted into glucose-6-phosphate, this yields 2ATP of energy. The glucose-6-phosphate is then broken down by phosphofructokinase (PFK) and lipase to produce pyruvic acid. In the lactic acid system the pyruvic acid is converted into lactic acid by lactate dehydrogenase (LHD), however in the aerobic system, due to oxygen being present, the pyruvic acid is converted into acetyl coenzyme A. Following this, the acetyl coenzyme A is combined with oxaloacetic acid to form citric acid before it enters the Krebs cycle, Stage 2. The Krebs cycle takes place in the matrix of the mitochondria, where the citric acid is oxidised (hydrogen removed), as a result carbon and oxygen are left; they combine to produce carbon dioxide and are exhaled out of the lungs. This yields 2ATP of energy. Although the by-product carbon dioxide has been eliminated there are still hydrogen atoms within the system. In order for the body to eliminate the hydrogen, the atoms of hydrogen enter the electron transport system, stage 3. The hydrogen atoms are split into ions and electrons by the hydrogen carriers NAD and FAD. The hydrogen ions are oxidised and combined with oxygen to form the by-product water, this is then either used or breathed out of the body while the hydrogen electrons provide the energy to resynthesise ATP. The electron transfer chain takes place in the cristae of the mitochondria and produces a yield of 34ATP. In total the aerobic system produces 38ATP; 2ATP during aerobic glycolysis, 2ATP during the Krebs cycle and 34ATP during the electron transfer chain.
ANALYSE/JUSTIFY – By doing specific aerobic training I will be able to increase the efficiency of the aerobic energy system and decrease my recovery time, increase cardiac hypertrophy and increase blood viscosity; all contributing to later fatigue and more energy during the match. This would mean I would not lose concentration or be technically lazy and I would therefore be able to keep defending against my defender efficiently until the end of the final quarter.
Corrective Practice
IDENTIFY – As I have the tendency to get tired in the final quarter of a netball match, this implies that I need to partake in a training programme that is specifically designed to improve stamina.
EXPLAIN – The training programme that I will design and used will be based on improving the effectiveness of the aerobic system with netball specific principles in mind. As netball involves periods of both high and low intensity with varying times of recovery I will try to incorporate this into my training by using a training programme based on fartlek training principles.
I will start with a 10 minute warm up run with dynamic stretches to reduce the chance of injury; I would then jog for 60 seconds, run hard (3/4 pace) for 90 seconds, jog for 45 seconds, sprint for 10 seconds, jog for 30 seconds, run backwards for 30 seconds, walk for 30 seconds and finally run hard for 60 seconds. I would repeat the cycle 3-4 times with a gap in between to drink water and rest; after which I would cool down at a steady pace for 10 minutes and stretch again. The mixture of high a low intensity ‘stations’ are specific to netball because in a game you are varying speed constantly. Before starting the programme and after the programme finishes I will carry out the multi-stage fitness test so that I can compare results and determine whether it has been successful in improving stamina. After each cycle I will record my recovery rate as this will provide me with evidence to see if the programme is working as the recovery rates will decrease if my stamina levels improve. I could also take a PH reading of the blood after the last cycle of the first session and the last cycle of the last session to see how the levels of lactic acid differ between the two. The programme is easy to record and compare as all 3 tests are very reliable and specific.
ANALYSE – My training programme will follow the principles of training: SPORT; specific – it is both sports specific to netball and designed to improve stamina (cardio respiratory endurance) and I will work at the same intensity and replicate the same actions that occur during a game; progression – as I continue with the programme I will increase the overload progressively. I will increase the duration of the stations and decrease the time of the rest periods as the programme progresses in order to continually improve my stamina; overload –I will use my recovery rate and lactic acid testing to test intensity of my exercise and increase it accordingly; reversibility – to prevent reversibility I will complete the circuit at least 3 times a week, I will also make sure that I am training in my aerobic training zone of 60% - 80% of my maximum heart rate (121bpm – 162bpm), to record this I will wear a heart rate monitor; tedium – to prevent tedium I will play different music when I am completing the programme, I will also change the warm up by introducing netball specific exercises such as quick, small side steps.
JUSTIFY – The fartlek training programme will help improve my stamina by improving the effectiveness of the aerobic energy system. This will help my game because I will know that I am physically fitter than my opposing player which in turn also gives me a mental advantage. This means that I can concentrate totally on the correct technique and reading my opposing player and the game itself. This will enable me to continually track and defend my opposing player, reducing her chances of getting the ball and increasing the chances of me intercepting a pass. This will improve my confidence considerably. The effect that this will have on my team mates is that they will feel completely confident in my abilities as a netballer and will result in a faster, more flowing game which increases our chance of winning and secures my place in the squad.