All physical training, whether cardiovascular, for strength or for endurance, is based upon the principle of exercise to overload, followed by recovery to a point better than that before exercising. Beneficial exercise causes mild damage which triggers the body into overcompensating for the apparent weakness - causing a net performance gain. Exercise to a point short of temporary fatigue will result in a correspondingly reduced gain, while excessive exercise will result in damage beyond the point from which the body can soon recover - causing a net performance loss.
The object of exercise is to bring about a training stimulus. Whatever exercise one does, should always be done to failure. All that precedes failure is just the means of getting to failure, and it is the failure and nothing else that triggers the training stimulus. Doing 10 reps when you could do 15 is pointless, as is doing a 2hr ergo when you could have done 10 minutes more at the same rate.
It follows that the training effect actually takes place after exercising. Therefore, sufficient rest between training sessions is the single most important element of any training regime. Insufficient rest will result in reduced performance gains or even performance loss.
A moderately fit person will experience maximum gains around two days after training. After this time the benefits of training begin to fade. Rules of thumb for a moderately fit person are that training around once per week is sufficient to maintain the same level of fitness (for the activity trained for); training three times per week would be about optimum; much more than this and such a person would become steadily less fit.
Recovery time and percentage performance gains are largely inversely proportional to the current fitness level, i.e. a very fit person will recover in a short time but with little performance gain, while an unfit person will have a longer recovery time but will experience large performance gains. So someone commencing a new fitness programme may experience maximum overall gains training once per week with 6 days recovery. A couple of months into a programme, training 3 times per week with recovery periods of around 60 hours may be optimal. In contrast, a world-level athlete at peak fitness may only occasionally require more than a good night's sleep to recover from a training session.
Any form of training is highly specific to the training activity. The training effect results in many complex and subtle changes of both micro and macro-biological in nature such as changes in muscle cell mitochondria and neurological changes. The training effect occurs almost exclusively over the range of movement subjected to fatigue. The greatest changes occur at the weakest point for a particular activity in a way suited to that activity. Therefore, if the training effect does not come from the activity being trained for, it should come from an activity which resembles it as closely as possible. In layman's terms, sprinting is sufficiently different an activity from cycling for there to be little, none, or even negative training cross-benefits. A rowing ergo however, provides sufficiently similar exercise to rowing for the fitness benefits to be almost wholly transferred.
Cardiovascular fitness is usually what many people mean when they say 'general fitness'. Although there are few physical activities which cannot be used to train the heart, lungs, and circulatory system, each activity has its own particular training effect. When switching activity to one not trained for, it will be the untrained weak links in the new activity that limit performance, reinforcing the specificity of training. 'General fitness' therefore, is best used to describe the fitness required to do the things most people do, which form a common set of highly specific tasks.
A rule of thumb for cardiovascular training involves raising the heart beat rate to 70%-90% of its theoretical maximum for a certain period of time, in the activity being trained for. As a guide, your theoretical maximum pulse rate is approximately 220 less your age. In practice this means that the average 18-22 year old will need to work sufficiently hard to raise the heart beat rate to between approx. 160 and 180 per minute for ten to twenty minutes, in order to achieve the optimum training stimulus.
Strength and Endurance Training
Muscle fibres are popularly regarded as being of two types - strength or fast-twitch fibres, and endurance or slow-twitch fibres - though in reality there is a continuous range from one to the other with a distribution determined genetically. Fast-twitch fibres are high-bulk, high-strength fibres which are recruited in small numbers and fatigue quickly. They can incur an 'oxygen debt' and rely upon the limited glycogen store in the muscle for their energy. They are associated with anaerobic respiration and short, high-powered events. Slow-twitch fibres are low-bulk low-strength fibres which rely upon aerobic respiration and can take much longer to fatigue under low loading. These are associated with aerobic respiration and long, lighter-load events.
All muscle fibres are subject to the same training effect after overload. Under light loading of any particular muscle, only the slower twitch fibres are recruited. The only way to overload in this circumstance is with time - equivalent say to a two hour low-rating ergo. Only those fibres recruited and subsequently fatigued will be trained, and so the performance gain will necessarily be optimised for two hour and longer events ! Under increased loading faster twitch fibres are also recruited, until the load is so great that maximum recruitment takes place, typically around 40%. With a high-load/low-repetition exercise a certain proportion of the recruited fibres will fatigue with each repetition and others will be recruited. Training to temporary muscular failure over around 8 to 12 repetitions is sufficient to have recruited and overloaded a high proportion of all fibres. This can be achieved in around a minute per muscle group and benefits all muscle fibre types - producing strength as well as endurance gains.
The crucial understanding in designing training exercises is that the benefit extends upward into the endurance range but never downward into the strength range.
The efficient training of muscle can bring about strength and endurance gains of around 1%-2% per recovery period. The number of muscle fibres remains constant but increased circulation produces a degree of swelling in fast-twitch fibres, resulting in an increase in muscle bulk. Cardiovascular benefits measured in terms of maximum aerobic respiration are about 20% over the first six to eight weeks of training, thereafter gains are very slow indeed. Providing the body has the ability to recover, these performance gains can be achieved at any age from a given base level.
The risk for rowers is in gaining useless muscle bulk if the exercise intensity is too high (e.g. short ergos to failure). Some rowers are almost incapable of gaining bulky (fast-twitch or strength) muscle, and so they can train as efficiently as they like. For others though, the training intensity needs to be carefully matched not to significantly undercut that of the event being trained for, so as to optimise the strength/weight relationships in a boat. The calculation requires the weights of the crew (inc. cox) and of the boat. The easy way is to train for a 20 minute event with 20 minute ergos, but this is rarely optimally efficient, and most usually shorter times would produce the same training effect.
It is said that our genes determine 99% of what we are capable of. You cannot increase your height, alter your bone structure, change the distribution or quantity of your muscle fibres, or for that matter, change sex. You can however, by efficient training, bring about huge increases in strength, become leaner, fitter, healthier, and generally achieve your own potential; and every body-type has a sport or activity to which it is best suited.
