I am now tapering for the Robin Hood half marathon, five days away. After a frustrating start to the year, in which a recurrence of arthritis limited my training for a few months, I have been able to train consistently for six months. I have achieved a greater training volume in those six months than I managed in the equivalent period last year, but frustratingly, my pace during tempo runs and progressive runs is slower this year than last year. In the event, last year I performed better than appeared possible in the light of my prior training paces, though at the cost of a somewhat painful final few kilometres. Again this year I will be hoping that I can lift myself to a higher level on race day. Despite the lower level of aerobic fitness this year, I am hoping that the greater training volume will have produced greater endurance. So I will be approaching the race with modest optimism that I can achieve a time near to last year’s time.
However, Sunday’s race is merely a stage in my campaign to run a respectable marathon at age 70. At this stage it would be premature to estimate a target time for a marathon in three years time. This year’s Half Marathon will provide something of a guide, though in fact my most important goal this year has been to establish that I can maintain an adequate training volume over a period of 6 months. Because my aging legs cannot cope with too much stress, I do about 20% of my training on the elliptical cross trainer. In the past 6 months, I have averaged 36 miles of running per week, together with an additional 1000 Kcal/week on the elliptical (equivalent to approximately 10 miles/week), giving an average weekly training volume equivalent to 46 miles per week. Although modest in comparison with a volume exceeding 100 mpw achieved by many younger marathoners, the key question is how to determine the optimum amount for me. The short answer is the that optimum amount is the amount that maximizes my response to training in the short term while building a base for future years.
What determines the response to training?
Four things determine the benefit you get from training.
- Life-time training experience
- The type, intensity and volume of the training
- Current level of stress.
There is little that we can do about our genes, but it is nonetheless, worthwhile reviewing the issue of genes briefly. The marathon performances of my younger days suggest that I was blessed with genes providing at least a moderate natural facility for distance running and also with the capacity to profit from training.
However in my present situation there is a third aspect of genetic endowment that matters: my ability to withstand the ravages of age. My parents both enjoyed moderately good health into their 80’s, so I have probably at least an averagely good selection of genes for longevity. The evidence from my own health so far is equivocal. Throughout my sixties I have suffered several health problems that have confounded any attempt to answer the question of how the tissues of my body are aging. These minor illnesses in themselves might be an indicator of increasing vulnerability to deterioration, but give little indication of widespread deterioration. In light of the fact that I have been able to train consistently for six months, my performance next Sunday will be potentially a good measure of the underlying rate of deterioration, uncontaminated by illness. To match the rate of deterioration predicted by WAVA, I can afford to drop 1 minute compared to last year’s HM time of 101:50. On present form, even 102:50 will be a challenge. However, if possible I would really like to set the clock back at least a little. My gold standard target is 100 minutes and silver standard is last year’s time: 101:50, though realistically I should be very pleased even to achieve 102:50.
Life-time training experience
In the short term, there is little I can do to alter life-time training experience, but in regard to the medium term future, there are important issues to consider. I suspect that running to and from school over 60 years ago, got me off to a good start. However the more pressing issue at my current age is the question of whether a large annual training volume at this stage will actually hasten deterioration. Excessive training can lead to chronic inflammation that is likely to damage tissues, possibly irreversibly. It is likely that a range of factors, including not only genes and past experience but also current lifestyle factors, especially diet, influence this. Thus, the question of how much training an individual can tolerate is likely to differ between individuals but is not necessarily immutable. But whatever my current ability to tolerate training might be, monitoring response to training to detect signs of over-training is likely to be crucial. I will return to this when addressing the effect stress in greater detail.
The type, intensity and volume of the training
Not only volume of training, but also type and intensity play a key role in shaping both the immediate response and also the long term effects of training. The pros and cons of different training regimes is too large a topic to deal with here, but it is perhaps pertinent to note that many athletes who have enjoyed years of high-level performance adopted a periodised program along the lines advocated by Arthur Lydiard, with a limited period of high intensity training and competition following a period of base-building in which the emphasis is on large volume of training at modest or low intensity. I started my current HM campaign with a period of Lydiard-style base-building, and am confident that this was beneficial
Current level of stress
Again we are brought back to the key issue of stress. As already discussed, avoiding cumulative tissue damage due to chronic inflammation is likely to be a key to the longevity of an individual’s running career. It is also a key determinant of the short term response to training.
It is widely recognised that the benefits of training arise from a training stress followed by an adaptive response during the recovery period. So stress is an essential element of training. The stress includes microscopic local trauma to body tissues including muscle fibres and other connective tissues, and also increases in stress hormones that exert a widespread influence throughout the body.
Microscopic damage to muscle fibres activates satellite cells, which are a type of stem cell that when activated combine with muscle fibres to extend and strengthen them. Thus in the short term heavy exercise results in loss of strength, but provided recovery between sessions is adequate, there is an overall upward progression. On the other hand, if recovery is not adequate, there is a risk of a downward spiral.
In the case of the hormonal responses, the increase in the stress hormone cortisol promotes a physiological state that mobilises body resources in a way that is helpful in the short term, but potentially damaging in the long term. The benefical short term effects include mobilisation of glucose and fats to fuel activity, but in the longer term, the result is muscle breakdown and deposition of fat. Cortisol has anti-inflammatory effects which in moderation tend to be helpful, but if excessive or prolonged, weaken the immune system. The mechanisms that determine the balance between the beneficial and harmful effects of inflammation are complex and remain something of a mystery. But, at least one thing is clear: sustained stress leads to damage to many tissues of the body. Fat is deposited around the viscera; chronic inflammation damages heart and skeletal muscle. Adequate recovery is essential, both for the sake of a constructive medium term training benefit, and also for long term health and fitness.
Therefore, during the past six months, as I have attempted to establish the limit of training volume and intensity that my body can cope with, I have performed the sub-maximal tests described in my posts on 25th June and 17th July 2013, on a weekly basis. Apart from one episode early in the year, when I had increased the training load too rapidly, I have avoided the suppression of heart rate at sub-maximal effort which is a warning of impending over-training. However on numerous occasions I have observed a moderate increase in heart rate at sub-maximal work rates, which I interpret as a sign of accumulating stress. In response to this sign of accumulating stress I have avoided demanding training session for a few days, and the signs of stress have resolved.
The apparently clear-cut benefit of this strategy for regulating training stress is that this year, I have managed to cope with a training volume over the 6 months from April to September that is about 17% higher than in the equivalent period last year. I am optimistic that this will stand me in good stead next year when I intend to train for a marathon. However, as outlined in the introduction, the somewhat disappointing outcome is that I appear to have a lower level of aerobic fitness (indicated by heart beats/km at a given pace in the aerobic zone) than at this time last year. Possibly this is due to a lower initial level of fitness arising from the disruption of training in the early months of this year. Alternatively, perhaps in my determination to make up for lost time, I might have pushed myself too close to my limit and therefore gained less benefit from the training. However, provided I have not seriously exceeded the limit, it is not unreasonable to hope that I might experience a similar improvement in performance during the taper this year as last year, and in addition will be able to draw upon enhanced endurance based on the greater training volume. I will start the half marathon on Sunday with the goal of testing this optimistic speculation.
Ewen, I will do my best to earn that mansion in Forrest for you, but I fear that your garden shed might be at risk.