Contrast Strength Training
This article originally appeared Peak Performance.
Contrast strength training is completed by lifting a heavy-load followed immediately by a lighter load. This is designed to improve power by preparing the muscles for maximal forceful efforts. The heavy-loading allows a greater activation of the muscles when the subsequent lighter loading is completed. Experts have claimed contrast training has improved power gains by three times compared to conventional programmes. Here is what the research says.
In one study, athletes performing explosive jump-squats, after a set of relatively heavy-resistance half-squats, were able to jump a statistically significant 2.8% higher than they were without the half-squats. The researchers suggested that this difference occurred because the heavy squats produced a ‘potentiation.’ This allowed muscles to contract more quickly and forcefully. This response was believed to be particularly noticeable in fast-twitch motor units.
Schmidtbleicher found that three maximal voluntary contractions of the quadriceps muscles led to a 3.3% rise in counter-movement jump height for both male and female athletes. The height of drop-jumps also improved. Explosive force and movement velocity were greater during bench throws after upper-body maximal voluntary contractions.
There is debate about exactly how this strength training should be combined within workouts. There are two schools of thoughts, the first supporting ‘complex training.’ Various sets of groups (complexes) of exercises are performed in such a way that several sets of heavy-resistance exercise are followed by several sets of lighter-resistance. ‘Contrast training’ alternate set for set, with a lightning-fast, light-resistance after a heavy one.
What the Aussies Found
Australian scientists study three different types of weight training on 11 female national or international hockey and softball players, aged 19-31. All subjects had been strength training for more than 2 years. The half-squats were performed on a Smith machine, with the down-position knee angle set at 90° and the intensity fixed at 3RM. This 3RM resistance averaged 120.5kg for the 11 athletes. The half-squat was the heavy-loading
The jump squats were completed with a modified Smith machine positioned over a force plate. A (light) resistance of just 30% of the 1RM half-squat (or about 32% of the 3RM half-squat resistance) was used as the load primarily because it had been previously found to produce maximal mechanical power outputs. This load averaged 38kg. A knee angle of 90° was selected for the squat position. The explosive jump for height was undertaken from this position so purely concentric action of the quads. This helped to control the influence of muscle pre-stretch on performance. Four reps of jump-squats were performed per set. The jump squats were the explosive exertion
In a ‘traditional’ workout, the 11 athletes completed three sets of light-load exercise (the jump squats), then three sets of heavy-load work (half-squats). A traditional programme moves from explosive to heavier loads throughout the workout. In a second ‘complex’ workout, all sets of the heavy-load half-squats were performed before the three sets of explosive jump squats. Finally, in the ‘contrast’ session, a set of the heavy half-squats was alternated with a set of the lighter jump-squats until three sets of each exercise had been performed. Each type of workout was preceded by identical thorough warm-ups, including stationary cycling, light static stretching and sub-maximal half-squats.
The Results
The complex workout produced worse jump-squats during the first set of jump-squatting than the traditional and contrast workouts. The fatigue associated with three sets of heavy-load 3RM half-squats maybe responsible. Heavy-load exercise may facilitate explosive movements. If the heavy-load work is extensive enough to induce significant muscular fatigue, it cannot facilitate explosive movements. A study by Verkhoshansky, novice track-and-field athletes who utilised heavy-loads before carrying out ‘speed-strength’ exercises achieved less improvement in explosive strength compared to those who put the explosive work before the heavy-loads.
Interestingly enough, the difference in power performance during the Australian study depended on the athletes’ strength levels. The 11 subjects were ‘median-split’ (with the median athlete ‘thrown out’) The five athletes with the highest 1RM values in one group and the five with the lowest in the other. 1RM averaged 116kg for the low-strength groups and 139kg for the high-strength athletes. After this split, statistical analysis revealed that the higher-strength group achieved a greater improvement in jump-squat performance with the contrast workout than with the traditional method. No such difference was observed in the lower-strength athletes.
Contrast Method Works for Strong Athletes
The higher-strength group achieved a 2% higher increase in maximal force and a 4% increase in peak power during squat jumping with the contrast training method than with the traditional method. Notably the lower-strength group tended to fare worse with the contrast workout, producing about 1% less maximal force and peak power than they had with the traditional session. The Australian researchers concluded that contrast training is advantageous for increasing power output in athletes with relatively high strength levels.
In supporting study, stronger subjects had greater gains in jump-squat performance after completing one set of heavy (5RM) squats than weaker individuals. Another study showed highly trained athletes displayed a significant neuromuscular potentiation response after heavy-load exertion, whereas less well-trained physical education students did not. These results could be due to better trained athlete’s having heightened fatigue resistance during initial heavy-load exercise. Athletes may have more responsive neuromuscular systems (their potentiation effect is greater).
The trend for performance during the jump squats decreased during workout. The contrast technique tended to produce the smallest decrement in performance. This maybe because the potentiation effect counterbalanced increased fatigue during the workout. The Australian researchers suggest that athletes should develop a very advanced strength base before considering the contrast method for power development.
Once a strength base is developed a contrast workout may follow these examples. An athlete that wants to improve raw running speed may complete explosive sprints, jumps, hops, bounds and high-intensity drills after heavy loads. These heavy load exercises maybe half-squats, partial squats or bench step-ups.
It is not known how long the potentiation effect actually lasts. An understanding of the ‘window of potentiation’ is lacking, and indeed this window might vary significantly from athlete to athlete. The research in this area is incomplete. It is clear that it might be advantageous as long as the potentiation window is fairly broad and limit the total number of heavy-load moves within an overall contrast workout.
Interestingly sub-maximal contractions of less than 85% of 1RM probably do not induce potentiation of the neuromuscular system. Squatting at just 80% of max, for example, might only serve to boost fatigue without potentiating anything. It is also believed that the heavy contractions must be sustained for several seconds at a time for potentiation to occur.
Warm Up is Important
Note that the contrast technique results have profound implications, not just for workouts but also for warm-ups. If the competitive effort involves explosive movement, it is clear that the inclusion of heavy-load exercise within the warm-up will be far more beneficial to a strong, experienced athlete. A traditional warm-up of lower intensity, which attempts only to activate the cardiovascular system and warm up the muscles, is inadequate. Several studies have already shown that warming up with a heavy-load produces enhanced ‘acute’ efforts (short-duration efforts which involve a quick burst of activity). The use of a preparatory heavy-load augments explosive countermovement jump height, drop-jump height, standing-long-jump-performance, general jumping ability and throwing speed.
Complex workouts, in which all the heavy-load sets precede the initiation of light, explosive work, appear to produce enough fatigue at the onset of the explosive training to reduce the quality of work carried out. Athletes who have developed a good foundation of strength seem to be able to carry out higher-quality explosive work with contrast training techniques than with traditional schemes, in which light, fast work precedes the heavy-load training.
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