An Interview with David Behm, PhD
by James Fitzgerald
As strength and conditioning goes, there are those that are in the lab applying theories to make things happen, and those that try to apply these theories at play in the gym. David Behm, PhD, an associate professor at the School of Human Kinetics and Recreation, MUN, PhD has been a constant advisor of informing those within the iron game of how to apply science into practice. David received his PhD from McGill, his Masters degree from McMaster, and his BEd and BPE from the University of Ottawa. He is a certified coach for tennis, squash, hockey, and badminton and has various experiences as an athlete at all levels. He has completed 25 research-related peer-reviewed published articles and a variety of other professional style conditioning articles and continues to strive for answers to questions of strength. I recently had the opportunity to ask David a couple of questions with respect to strength and conditioning.
JF: With your latest contributions on optimal warm ups for strength and power, what would you consider to be an effective preparatory method for strength/power athletes in a resistance trained setting?
The traditional wisdom concerning physical preparation prior to an athletic event would include a cardiovascular warm-up activity followed by stretching and then physical practice of the specific movements involved the sport. Stretching is pervasive throughout sport and therapy. It has been reported to increase range of motion (ROM) (Safran et al., 1989), prevent injuries (Worrel et al., 1995), and increase performance (Worrel et al., 1995). However, the latest research has demonstrated that static stretching is detrimental to force output (Fowles et al., 2000, Kokkonen et al., 1998, Nelson et al., 1998, Behm et al. 2001), muscle activation (Behm et al. 2001) and power (Young and Behm 2002). Studies have reported decrements in force and activation (EMG) of 12 and 20% respectively (Behm et al. 2001). It is difficult for many people to believe that such a widespread practice could actually reduce performance, when conventional knowledge for generations has told us to stretch before athletic events. They might argue that some of the studies were unrealistic, since they utilized 20 minutes of stretching for a single muscle group. The only athletes that might stretch for this extended period of time would be gymnasts or contortionists for the Cirque de Soleil. However a recent study by Young and Behm (2002) used only 3 repetitions of 30 second stretches for the quadriceps and plantar flexors and still found reductions in squat jump performance. Thus, how should an athlete prepare for their event?
Once again Young and Behm’s study can provide some insight. We had subjects either stretch, run for 4 minutes, stretch and run, stretch, run and practice jump or do nothing (control). The best performances were achieved with the run only, with the worst performances with the stretch only and no significant change with the stretch and run or run, stretch and practice jumps. It seems that running to warm-up the muscles was a positive action and stretching was a negative action. Thus anytime stretching was added to possible positive actions, the stretching reduced the positive effects of the other action (i.e. running or jumping). Unfortunately we did not have a group perform running and jumping only, which may have been two positive actions prior to performance. Hence, I would recommend athletes to warm-up their muscles with a dynamic activity that increases muscle and core temperatures (start a sweat) and then follow with activities specific to the sport. For example, a baseball player would have a warm-up run followed by low velocity and restricted range of motion throws, swings (bat), and runs. As the muscles become even more pliable, the athlete would increase the velocity and range of motion till they achieve game conditions.
There are still questions regarding the stretching controversy. All the studies utilized maximum tension static stretching. Perhaps less intense stretching might provide an increased ROM without the detrimental effects. Secondly, how long do the stretching-induced decrements persist? Fowles and Sale (2000) measured the decreases for an hour after 20 minutes of stretching. If the stretching-induced impediments last for an hour but the range of motion increases persist for 2 hours, maybe it would be a matter of just starting the stretching earlier. Our laboratory intends to investigate these questions in the near future.
JF: While on the “conventional thinking” mindset, current popular speed, agility and quickness protocols emphasize tools and gadgets that claim to somehow mimic the sporting situation (ladders, cones, tubes, balls) without strength training; what are your thoughts on increasing speed, agility and quickness as it relates to a “strength trained” setting focusing on repetition speed, intent of movement and contraction velocities?
An athlete with less than optimal technique can improve their speed by improving that technique and optimizing their economy. These modifications can be accomplished on the track, field, or ice (i.e. hockey), by practicing the exact movement or using a variety of tools or implements to simulate the movement. Whereas, this type of training can economize movement and provide overload resistances based on body mass reaction forces, similar or greater overload resistances can be provided over longer durations in the weight room. If two individuals possessed the exact same technique, then the individual who could move their legs faster (stride rate) and cover more ground in a single stride (stride length) would be the eventual winner. In particular, physiological components (i.e. power, reactive strength) associated with stride length may be improved in the weight room. However, there are a couple of important questions to answer first. First of all, would an athlete gain more speed by spending a greater time in the weight room than on the track? Secondly if time in the weight room is necessary, what is the optimal means of training speed, agility and quickness?
Zatsiorsky’s concept of the strength deficit may help in determining the appropriate time in the weight room. He proposed an equation that gave a general indication of the importance of resistance training to a particular sport. The proportion of time spent resistance training would be dependent on the ratio between the forces exerted during the sport and the maximum force exerted in the weight room. For example, a badminton player does not exert great forces when striking the shuttle. Due to the low mass of the racquet and shuttle, racquet head speed alone provides the greatest impetus to the speed of the shuttle. Thus, since small forces are exerted on the court compared to the maximum force the individual could exert, a badminton player need not spend inordinate time in the weight room for upper body strength. However, an offensive lineman in football or a rugby player must move very large opponents. The forces exerted on the field are maximal forces, comparable to the maximum forces that could be exerted in the weight room. Obviously, a football lineman and a rugby player would spend a lot of time in the weight room. In terms of speed, the time in the weight room would be substantial for someone who has to overcome great forces or inertia such as a 100-meter sprinter. The acceleration from the blocks for a 100-meter sprint would involve maximal forces. An athlete running 1500 meters does not use maximal forces at the start and their momentum throughout the race provides significant contribution to their stride length, such that they would probably never exert maximal forces. Although a soccer player periodically sprints at top speed, they are almost always in motion and thus there is less inertia to overcome and more momentum to help attain and maintain speed. Hence, a soccer player would not spend as much time resistance training for speed as a sprinter.
Once in the weight room, what is the optimal means of training for speed, agility and quickness? Improvements in speed, agility and quickness would be related to 3 major factors that can be modified in the weight room; a) co-ordination b) rate of force development and c) force.
Stride length can be improved if the leg power is increased. Since power is a function of force and speed, what needs to be performed in the weight room? It could be suggested that just increasing the force of the appropriate muscles with resistance training would provide improvements. While this is true, it is the ability to exert those forces at high speeds that provides power, so if both factors can be improved with a specific routine it would be more efficient than just improving one aspect (i.e. force). The rate of muscular force development is dependent upon the fiber type composition of the muscle (more fast twitch versus low twitch) and the frequency of stimulation from the central nervous system. Whereas, you cannot make substantial changes to your fiber type composition you can ameliorate your firing frequencies. This can be accomplished with either increasing the contraction or movement speed. Our article (Behm and Sale 1993) indicated that it was the intent to contract explosively that provided a high velocity specific effect. While there have been further articles that have both substantiated and refuted our findings, I have received feedback from coaches in North America and Australia indicating that they have used high loads with explosive (intent to contract at a high rate) contractions and found significant improvements in performance. The inertia of the high loads cause the resistance to move slowly but the explosive nature of the contraction against a high load results in increases in both rate of force development and force creating greater power.
A refinement to the explosive high load contractions would be to attempt to simulate the stride movement so that the correct muscle groups are taught to increase their firing frequencies. As mentioned previously, co-ordination is an important aspect of speed. The athlete not only wants the prime movers to be optimized (force and rate of force development) but the synergists as well. Thus movements that most closely mimic the sport action would serve this function. This training could include Olympic lifts with a staggered stance, sprint leg actions against tubing, high amplitude plyometrics and other training routines.
Whereas this type of training should improve stride length, it probably will not have a significant impact on stride rate. Dr. Warren Young at the University of Ballarat in Australia has shown a strong correlation between sprinting speed and a ratio of vertical jump height and contact time. Athletes who could jump the highest with the shortest contact time typically could run the fastest and jump the highest. Some athletes may have great vertical jumps but develop their power from impulse (force exerted over time). A typical example might be a shot putter who can develop great power but may not have great sprinting speed. Thus, somehow short contact times must be developed to enhance the other half of the stride rate and stride length equation. Whereas reaction time would have a significant genetic component, contact times can be improved to a certain degree with low amplitude plyometrics. Quick foot and leg movements over low obstructions will not change the intrinsic contractile velocity of the muscle fibers, but will improve the co-ordination of the athlete to activate and relax the appropriate prime movers, synergists and antagonists to allow them to traverse the ground at a greater speed.
In conclusion, greater speed, agility and quickness can be accomplished by improving leg power and leg speed. Leg power should be developed by using high contraction speeds (explosive) against high resistances, which can be accomplished with resistance or body weight (high amplitude plyometrics). Stride rate can be improved by decreasing contact time with low amplitude plyometrics (explosive contractions against low resistances) or over-speed training (using devices such as treadmills, decline running and vehicles to move you at speeds exceeding your normal maximum speed). Finally and hopefully obviously, the athlete must take their training improvements out to the track, field or ice surface and refine the co-ordination needed to move as efficiently as possible.
JF: Finally Dave, I have always known you to appreciate and show an interest in strength training in research and the practical setting, which is hard to come by in a successful scientist. From your personal experience, what essential components of conditioning can individuals take from the lab and put into practice in the gym?
I do attempt to apply my research findings to my workouts. However before I disclose my workout practices, some background information is probably necessary to rationalize what I do. First of all, I am a former university football player who was drafted into the Canadian Football League, but I was too slow to make it as a running back in the pro leagues. I also played junior hockey and baseball. When I realized that I was not going to make a career as a professional athlete, I shifted gears to racquet sports and running. Thus, these days as a 46 year old father of a new baby, I try to play squash twice a week, tennis once a week, recreational hockey once a week in the winter and touch football once a week in the summer/fall. I also try to run 3-4 times a week at noon hour. Hence, there is not much time left for resistance training. However, I do try to get in 2 noon hour workouts per week. As a competitive football player, resistance training was a priority, but as a competitive racquet sport athlete (#1 ranking in Newfoundland squash and #1 over 35 year old tennis player in Newfoundland), I do not need a 300 lb plus bench press or a 500 lb plus squat anymore. My goals are to maintain or modestly increase my strength and power with the shortest possible workouts possible. Thus, I only workout twice a week for 20 minutes each. Even with this minimalist training procedure I still experience strength gains.
Since I participate in a lot of sports that involve running and explosive changes in direction (squash, tennis, touch football and hockey), I only concentrate on my upper body in the weight room. By concentrating on multi-joint exercises, I can stress most of the major muscle groups with only a few exercises. My workout consists of either:
flat or incline bench with an Olympic bar or dumbbells: pectorals, deltoids and triceps
pull-ups, lat pull down or seated rowing: latissimus dorsi, rhomboids, lower trapezius, biceps
abdominals (change exercise from workout to workout): rectus abdominus, obliques
back extensions: erector spinae
I never do the same exercises two workouts in a row, ensuring that the muscle is stressed in a slightly different manner each time.
Strength is obtained not only from muscle hypertrophy but also from neural adaptations and improved muscle co-ordination. I attempt to stimulate all 3 areas in my abbreviated workouts. While there are many factors that contribute to hypertrophy, probably the most important is tension on the muscle. I attempt to use high intensity resistance in my 3 sets per exercise routine with only 6-8 repetitions. The high resistance forces me to control the weight in a well-co-coordinated manner and hopefully integrate the most appropriate prime movers and synergists while inhibiting inappropriate antagonist contributions. Furthermore, the high resistance will ensure that the fast twitch fibres will be targeted early in the set rather than later as would be the case with low to moderate resistance. Thus, rather than placing stress on the fast twitch fibres for only the last few repetitions, they should receive adaptation-invoking stress for most of the set.
Co-ordination and motor control can also be stressed by performing the exercises with an unstable environment. Our research has shown that forces are significantly reduced dependent upon the severity of the instability. Hence, if you are too unstable then the forces drop so substantially that there is insufficient tensile stress on the muscle to cause it to adapt. But our research has also found the muscle EMG is similar whether the resistance is exerted on a stable bench or on a Swiss ball. We concluded that if the force is less, but the muscle activation is the same, then the muscle must have a greater role as a stabilizer rather than just a prime mover. This occurrence would be typical of sport situations where you almost never lie on your back and push a resistance straight over your chest, but rather exert forces while on the move, on one leg or in a myriad of other unstable positions. We also examined stable versus unstable squats and found that the core stabilizers were activated to a greater degree with the unstable squats. This increased activation of core stabilizers would again be important for force output in real-life activities as well as protecting the trunk. Since tension may be the most important factor affecting muscle strength adaptations, I perform some but not all of my exercises on Swiss balls. However I do not try any circus-like moves, since as I mentioned previously, the force output drops rapidly with severe instability and I would then only be working on balance and not strength.
My article in 1993 in the Journal of Applied Physiology found that high velocity strength adaptations can be achieved with the intent to contract explosively. In other words, the muscle can become more powerful (force x speed) even if the limbs move slowly due to the inertia of a heavy weight. As long as the individual attempts to blast the weight up as quickly as possible, there should be a high frequency signal emanating from the brain to teach the muscle to contract rapidly against force. Thus, since power is important in all the sports I play, I attempt to accelerate the weights as fast as possible concentrically then lower them slowly to emphasize the eccentric portion of the contraction. There are a number of papers showing that the greatest hypertrophy occurs when eccentric contractions are emphasized in addition to the concentric. A slow eccentric component will also emphasize another factor contributing to hypertrophy; increased time under tension.
In summary, I feel that significant strength gains can be achieved with minimal weight room time as long as the muscle is intensely stressed with each exercise. This stress can be accomplished through a combination of high resistance, varied exercises, explosive contractions, moderate instability, and a concentrated effort on prolonging the time under tension for the eccentric contractions. At least that is what seems to work for this middle-aged, over the hill, professor / pseudo-athlete.
This article brought to you by James FitzGerald, Strength Coach (optimumtraining@shaw.ca)
