2IntroductionThe taper is a training phase before competition during which the training load is progressively reduced for a variable period of time to allow for physiological and psychological recovery from accumulated training stress, with the aim of maximizing competition performance.The relationship between the reduced training load during the taper and performance benefits is well established, allowing investigators to make training recommendations to optimize pre-event tapering strategies
3The aim of this lecture is to compile and synthesize the present knowledge on tapering induced physiological changes in athletes and assess the possible relationships between these changes and performance benefits of the taper.
4Cardio respiratory Changes Maximal Oxygen UptakeMaximal oxygen uptake (VO2max) can increase or remain unchanged during periods of taper before competition in highly trained athletes.
5Effect of the taper on maximal oxygen uptake Decrease in VO2max during the taper would most likely be indicative of a poorly planned tapering strategy in endurance athletes.
6Neary et al(2003) have reported VO2max enhancements of 6 Neary et al(2003) have reported VO2max enhancements of 6.0% in cyclists reducing their weekly training volume by 50% during 7 days.Neither an increase in VO2max nor a simulated performance gain was observed in cyclists reducing training volume by 30% or 80% during a 7-day taper.
7The same group also reported an increase in VO2max (2 The same group also reported an increase in VO2max (2.5%) and simulated performance (4.3%) in cyclists who maintained training intensity but reduced training volume.In contrast, cyclists maintaining training volume but reducing intensity only showed statistically non-significant improvements in VO2max (1.1%) and simulated performance (2.2%).intensity is a key factor for the maintenance or enhancement of training-induced adaptations and optimization of sports performance.
8Jeukendrup et al (1993) – cyclists - a 4 Jeukendrup et al (1993) – cyclists - a 4.5% increase in VO2max, a 10% higher peak power output and 7.2% faster 8.5km outdoor time trial at the end of 2 weeks taper.Margaritis et al (2003) – triathletes - 3% gains in both VO2max and simulated performance during a14-day taper.Several investigators have observed unchanged VO2max values as a result of a taper.
9Collectively, these studies generally show improved or stable VO2max and performance gains after a taper, particularly where training intensity has been maintained.
10Economy of MovementThe economy of movement is defined as the oxygen cost of exercise at a given submaximal exercise intensity.Houmard et al (1994) – distance runners - a 7% (0.9 kcal/min) decrease in calculated submaximal energy expenditure when running at 80% peak oxygen uptake on a treadmill.Dressendorfer et al (2002) – cyclists – no marked improvement in economy in male cyclists tapering for 10 days.
11The investigators suggested that an elevation in the muscle’s mitochondrial capacity, along with neural, structural and biomechanical factors could explain improvements in economy with the taper
12Cardiac Function and Dimensions Efect of the taper on resting, maximal & submaximal heart rate
13A possible explanation for the inconsistent findings could relate to opposite effects on maximal HR of blood volume expansion and the level of catecholamine depletion that may have been incurred during the preceding phase of intense training.
14Cardiac DimensionsHaykowsky et al (1998) – swimmers - no marked change in diastolic or systolic cavity dimensions, ventricular septal wall thickness, estimated absolute or relative left ventricular mass, stroke volume, cardiac output, cardiac index or fractional shortening.
15Ventilatory FunctionNeary et al (2003) – cyclists - Peak ventilatory volume was unchanged but the ventilatory equivalent (VE/Vo2) for oxygen declined.
16Haematology Balance Between Haemolysis and Erythropoiesis Intensive athletic training can results in decreased red blood cells, haemoglobin concentration and haematocrit that have variously been attributed to a haemodilution caused by training-induced expanded plasma volume, an imbalance between haematopoiesis and intravascular haemolysis, or iron deficiency.
17Taper-induced increases in blood and red cell volume have been reported in highly trained that associated with an elevation of plasma renin activity and vasopressin concentration during exercise and a chronic increase in the water-binding capacity of the blood.Haemoglobin concentration and haematocrit increased during the taper that attributed to a decreased haemolysis and a net increase in erythrocytes.
18Metabolic Changes Energy Expenditure/Energy Balance A certain level of muscle mass loss may have taken place during the taper and suggest that athletes tapering for competition should pay careful attention to matching energy intake in accordance with the reduced energy expenditure that characterizes this training period.
19Substrate Availability and Utilization During submaximal-intensity & maximal exercise RER values have been shown to remain unchanged after tapering.These results suggest that the substrate contribution is not modified by a taper.This lack of change may be related to stable aerobic-anaerobic work production and oxygen deficit during the taper.
20Blood Lactate Kinetics Significant relationships were seen between increases in peak post-race blood lactatelevels and competition performance enhancement (r = 0.63).
21Muscle GlycogenMuscle glycogen concentration has been shown to increase progressively during periods of taper.
22Biochemical Changes Creatine Kinase Blood levels of creatine kinase (CK) have been used as an index of training-induced physiological stress.Various studies have shown decreases in CK levels during the taper.
23Hormonal ChangesTestosterone, Cortisol and the Testosterone : Cortisol RatioThe plasma levels of testosterone (T) and cortisol(C) could represent anabolic and catabolic tissue activities, respectively.
24CatecholaminesPlasma and urinary catecholamine concentrations is a means to monitor training stress & identify overreaching or overtraining in athletes.the change in plasma catecholamine concentration could be a useful marker for monitoring recovery associated with the taper.
25Neuromuscular Changes Strength and PowerIncreased strength and power as a result of a taper have been a common observation in different athletic activities.
26The mechanisms responsible for the taper induced improvements in muscular strength and power Changes in enzymatic activitiesMuscle fibre characteristicsMuscle Fibre SizeMetabolic PropertiesContractile Properties
27Immunological Changes Many aspects of the immune system exhibit a range of responses to acute exercise and prolonged training in athletes preparing for competition:Increased leukocyte cell counts particularly neutrophils and lymphocyte subsetsDecreased functional activity of the neutrophil respiratory burstDecreased natural killer cytotoxicityDecreased response to mitogen-induced T-lymphocyte proliferationDecreased concentration of mucosal immune parameters, such as secretory immunoglobulin AImpaired delayed-type hypersensitivity response (T-cell function)Unchanged or increased circulating concentration of cytokines
28Psychological Changes Optimization of an athlete’s physiological status resulting from a well designed tapering strategy is presumably accompanied by beneficial psychological changes, including:Mood statePerception of effortQuality of sleep
30Taper planning Reduction of training intensity Training intensity is an essential requirement for maintaining training-induced adaptations during period of taper.Mujika et al (2000): HIT during the taper correlated positively with the percentage change in circulating T levels in well-trained middle- distance runners.
31Reduction of training volume Standardized training volume reduction of % have been shown to be a valid approach to retain or slightly improve training-induced adaptations in well-trained athletes.
32Reduction of training frequency For moderately trained individuals 30-50% and for highly trained athletes, much higher training frequency, >80% of pretaper values, should be recommended, especially in the more “technique-dependent” sports such as swimming.
33Duration of the taperDuration of a taper for individual athlete is one of the most difficult challenges for coaches and sports scientists.Positive physiological, psychological & performance adaptations have been reported as a result of taper programs lasting 4-14 d in cyclist & triathletes, 6-7 d in middle- and long-distance runners, 10 d in strength trained athletes & d in swimmers.