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Monday, January 25 2021

Rowing Physiology

Energy Systems

In order to train effectively for rowing we need to understand how the body produces energy. Listed below is a brief description of the 3 energy pathways, aerobic, anaerobic, and creatine phosphate system and how they relate to rowing.

ATP (Adenosine Triphosphate) – ATP is the body's energy source.  Just like gasoline is the energy source for a car, ATP is needed for the body to move the muscles.   How efficiently and quickly a muscle can produce ATP, determines how much work the muscle can do before it fatigues. While some ATP is stored in a muscle cell, the supply is limited.  Muscle cells must replenish ATP in order to keep moving.  ATP is produced by three biochemical pathways: aerobic system, anaerobic glycolysis (anaerobic system) and the creatine phosphate system (cp system).  

Aerobic System- Aerobic means with oxygen.  Oxygen combines with fat (fatty acids) and carbohydrates (glucose) to produce ATP.  The waste products of water and carbon dioxide (C02) are easy for the body to deal with and will not lead to muscle fatigue.   The benefits of aerobic training are an increase in cardiac output with an increase stroke volume.  New capillaries are produced in the active skeletal muscle which will increase the amount of oxygen exchanged in the muscle.  There is also an increase in mitochondria density, which means more of the muscle cells are occupied by mitochondria.  Mitochondria are the site of ATP production.  The greater the  number of mitochondria, the greater the aerobic production of the cell.  The aerobic energy system produces much more ATP than the anaerobic systems.  This is because fat yields nine calories of energy per gram and carbohydrate (glucose) and protein only yield four calories per gram. Aerobic training usually takes place at heart rate levels of 65-80% of max, depending on the athlete.  When training the aerobic system it is important not to move above your anaerobic threshold.  Moving above your anaerobic threshold will decrease the benefits of increased mitochondria, number of capillaries, and use of fatty acids.  Aerobic training is sometimes broken down into two categories, Utilization 1 and Utilization 2.  Utilization is the body's ability to "utilize" oxygen.  I can't stress enough that the benefits of aerobic training will not be seen if the training it too high.  See training charts below about specific training levels.  The increased cardiac output combined with the increased number of capillaries not only yields a greater aerobic capacity, but also an elevated anaerobic threshold (see anaerobic threshold).  The aerobic system provides about 75-80% of the energy requirements of a 2000M race.  For a 1000M race it is approximately 50%.  It takes approximately 60-90 seconds to activate the aerobic system in a rowing race.

Anaerobic System – When oxygen is not readily available, the body will start to produce energy anaerobically.     Glucose it the primary substance used to produce ATP. The breakdown of glucose to lactic acid is also termed anaerobic glycolysis.   The by-products of anaerobic glycolysis are lactic acid (lactate), hydrogen ions and heat.  The depletion of glycogen and the accumulation of lactic acid and hydrogen ions in the muscles will reduce the ability of the muscle to contract.  Lactic acid accumulation will cause pain and burning in the muscles.  Energy produced from the anaerobic system alone will provide energy for about 2-3 minutes or 20-25% of the energy requirements for a 2000 meter race.  For a 1000 meter race approximately 50% of the energy required will be from the anaerobic system.  This would include the period of 30-90 seconds after a start and the last 60-90 seconds of the race.

Creatine Phosphate System – Creatine phosphate is a high energy substance, similar to ATP which is stored in the muscle.    It can provide the energy to re-synthesize ATP rapidly, but the amount stored is only enough for about ten seconds.  This process is conducted in the absence of oxygen, but does not produce lactic acid (also referred to as the alactic system).  This is a short term power supply which will provide energy for the start of a race.  The energy contribution is a small percentage of the total energy requirements of a rowing race.

Lactate – As mentioned above, lactate is the by-product of oxygen and co2 when the body produces energy.  At lower training intensities lactate is produced at a rate that can be absorbed by the body faster or at the same rate as it is produced.  As training intensity increases (higher heart rate) lactate is produced faster than the body can get rid of it.  The end result is that your muscles start to burn and exercise starts to become uncomfortable and at some point you will not be able to continue going.  Blood lactate levels are very important to exercise physiology.

For more detail on lactate -Lactate is the product of incomplete oxidation of glucose. When the oxidation of one unit (molecule) of glucose stops at lactate it produces only 4 units (molecules) of ATP. When there is enough oxygen to metabolize glucose all the way to carbon dioxide and water 32 molecules of ATP are produced. The lactate produced by muscle exertion is cycled to the liver where it can be converted back to glucose or if enough oxygen is available it can be metabolized by muscle to produce ATP. At lower training intensities lactate is produced at a rate that can be utilized by  liver and muscle so that the blood level of lactate does not keep rising. As training intensities increase the muscles produce lactate faster than the liver and muscles can use it. The end result is that exercise starts to become uncomfortable, the muscles burn , breathing becomes labored and eventually you have to stop or slow down. Blood lactate levels are a very important tool in exercise physiology.

Sources:

Baechle, T.R. Editor. 1994. Essentails of Strength and Conditioning/National Strength and Conditioning Association. Champlain, IL: Human Kinetics.

Davenport, M.L. - Editor. 2004. Level II Candidate Manual. US Rowing Coaching Education Program (7): 100-108.

Hagerman, F.C. 2000. Physiology of Competitive Rowing. Exercise and Sports Science (54): 843-872.

Nilsen, T.S. 2001. Intermediate Rowing Physiology. FISA Coaching Development (2): 34-51.

Nolte, V. - Editor. 2005. Rowing Faster. Champlain, IL: Human Kinetics.

updated: 13 years ago