For specific details of rides, see the VRS Endurance Workouts Page
Structural and physiologic changes in the heart will occur with increases endurance exercise. Notably there is marked concentric and eccentric dilation of the heart muscle. However, the significance of this is unknown, as the cardiac changes on echocardiogram do not necessarily correlate with the best performance. Certainly, it has been show that these changes are not necessary to become an elite athelete. Unlike pathologic (BAD) cardiac hypertrophy, diastolic function remains normal. 9
Performance is related strongly to : (1) Lactate threshold at a high percentage of VO2Max, and (2) ability to maintain lactate levels below 4mmol/L at high output.9
During ultra-endurance events, (lasting over 10h such as triathlon), there is a risk of cardiovascular fatigue with increasing heart rate and decreasing stroke volume. Changes are quickly reversed with 24h of rest. However, it is possible, that excessive workload in intensity and duration could potentially cause irreversible damage.
A test of 4000 m pursuit cyclists revealed that to maintain a paceline a 60 km/h, a cyclist must produce 607watts in first position, 430watts in second position, 389watts in third position, and 389watts in fourth position.14
When 13 elite cyclists were tested for plasma lactate concentration at steady state, it was found that elite cyclist have the highes maximal lactate at steady state ever recorded. 16
Anaerobic training is mandatory for competetive cyclists. Unlike aerobic training which has body-wide benefits for the cardiovascular system, aerobic benefits are localized to the muscle being exercised, and include anatomic, biochemical, and neurologic adaptations. To be useful, anaerobic training must be very intense, and performed to near exhaustion. 17
Despite the need for anaerobic training, a study of endurance athletes revealed that training confered no advantage in decline of plasma lactate levels during passive recovery at maximal effort. 23
A Study of elite level USCF road cyclists and NORBA off road cyclists revealed that physiologic responses to lactate threshold and maximal exertion were similar. However, female USCF cyclists had a greateer maximal aerobic power and max heart rate when compared to NORBA women. In contrast, male USCF cyclists produced greater power at lactate threshold and greater power at max heart-rate than male NORBA cyclists. 21
New research shows that respiratory muscle fatigue may be a limiting factor for exercise. When athletes engaged in specific respiratory muscle training (Five 30 minute sessions per week for 4 weeks), exercise tolerance was improved. Athletes had decreased minute ventilation and decreased blood lactate concentration for a given workload. In addition, respiratory trained athletes no longer suffered from feelings of breathlessness during intense workouts.37
In a US study to research the effects of cross training, runners were divided into two groups, a run-only and a cross-train group. The study found that both groups responded equally well to training, and changes in performance were equal in both groups. In addition, there was not decline in running economy in the cross training group, suggesting that technique does not suffer from the decreased running time. 41
Interestingly, it is possible that high levels of endurance training may be detrimental to rapid force development. In a study of military recruits, basic endurance training was found to increase endurance ability but decreased ability of vertical jump.100
In general measurement of heart rate, and determination of Lactate Threshold by intense testing is the prefered method of determining training load. For a simple measure of LTHR, the heart rate at ventilatory threshold should be considered. At ventilatory threshold, the athletes breathing becomes noticeably labored. This exertional level is often very close to LTHR, and studies have shown the VT to be closely related to maximum heart rate and time trial heart rate. 32
The preferred method for gauging workload is likely and ergometer or bicycle power meter. Surprisingly, a German study found that comercial ergometers and bicycle power meters had excellent correlation with one-another. Thus, a workload measured on one machine is very likely to be close to the same workload on another machine.33
Traditionally, cyclists have been tested several times throughout the season to measure LTHR, as it was felt that LTHR would increase through training. However, a recent study showed that despite marked improvement in power output, the actual LTHR and heart rate zones did not change throughout the season. That is, although that for any given heart rate the power was increased by training, the heart rate zones did not need to be modified throughout the season. This suggests that a single test of LTHR early in the season may be sufficient for determination of heart rate zones for the entire season.34
A study at Montana State University found that actual uphill time trial performance was best estimated by an assessment of Maximum Power Output per Kilogram Body Weight. The study found that the relationship between uphill TT performance and VO2 max or watts at ventilatory threshold was less reliable. 36
Although not practical for most situations, there is evidence that EMG behavior of dynamically working muscles may be an indicator of blood lactate and plasma catecholamine changes during exercise. 42
Although the lactate response can be used to measure workload for an individual athlete, the plasma lactate response is not predictive of performance. For similarily well-trained athletes, comparison of plasma lactate response does not predict which cyclist will be a more powerful cyclist.46
Where do pro riders keep their heart rates during racing ? A study in Spain looked at HR intensity during the Tour de France and Vuelta a Espana, and foud the following results. 11
|
Measured Variable |
Average in Vuelta |
Average in TdF |
|---|---|---|
|
Average Heart Rate / per min |
134 +/- 18 |
134 +/- 19 |
|
Mean Stage Length / min |
269 +/- 122 |
260 +/- 120 |
|
Time spent over Anaerobic Threshold / |
17.5 +/- 16 (13%) |
25 +/- 26 (17%) |
|
Time in Sub Threshold / min |
75 +/- 47 (30%) |
80 +/- 48 (30%) |
|
Time in Aerobic (Zone I/II/II) / min |
97 +/- 57 (32%) |
90 +/- 55 (32%) |
|
Time in Recovery Zone |
80 +/- 60 (25%) |
65 +/- 70 (25%) |