This is an excerpt from Developing Agility and Quickness 2nd Edition PDF by NSCA -National Strength & Conditioning Association & Jay Dawes.
It is an essential and standard practice for athletes to warm up before they practice or compete. The purpose of a well-designed warm-up is to enhance performance and decrease the likelihood of injuries. The warm-up also provides an ideal time to learn and rehearse movement skills such as jumping, landing, accelerating, decelerating, and the other various modes of locomotion. The opportunity for mental preparation that this segment of the training session provides is equally important because it sets the tone for the work to follow. An appropriate warm-up reaps several physiological benefits that can positively affect an athlete's performance. The warm-up should increase blood flow to active muscles, raise core body temperature, enhance metabolic reactions, and disrupt temporary connective tissue bonds. These effects can aid the athlete by yielding improvements in rate-of-force development, improvements in reaction time, improved oxygen delivery to the lungs and working muscles, and improvements in acute measures of muscle strength and power. In addition, the increased production of synovial fluid located between the joints will acutely enhance the dynamic flexibility, or mobility, of the joints. Another benefit is that the warm-up helps facilitate the breakdown of glycogen, which is the source of energy most often used for exercise; this translates to more energy available for the athlete.
The mental aspect of the warm-up often does not receive the attention it deserves. The warm-up provides the perfect opportunity for athletes to shut off concerns from the outside world and concentrate on the activities that are about to commence. Effective warm-up sessions direct focus and active participation by both coaches and athletes; even responsible athletes can benefit from performing movements under the diligent eyes of the coach. This means that the coach must actively engage in cueing and teaching these movements to help athletes create the appropriate intent with each movement. For example, a coach instructing athletes on proper plyometric mechanics during a practice session might cue the athletes during a warm-up to pretend they are landing on hot coals; this image could help prepare them for quick landings and explosive takeoffs. Reinforcing proper cues during the warm-up offers a less stressful platform for learning.
Proper posture and body positioning are critical in all physical activities for optimizing performance and reducing injury risk and for maintaining body balance and the proper arrangement of supporting structures. Research supports the contention that correct posture is a prerequisite of a healthy lifestyle but today's athletes live in a world that does not necessarily promote good posture. Excessive use of phones and computers, carrying heavy school or work bags, and poor posture while studying or watching television are just a few examples of habits that prohibit the maintenance of correct posture. The warm-up offers a good opportunity to educate and then reinforce proper posture and body positioning. Here are some simple ways to address this issue.
- Keep the head up at all times and always look straight ahead.
- When landing and decelerating, hinge at the hips and do not round the back to dampen the force with the hips and knees.
- Maintain proper foot alignment and spacing when jumping and landing; for example, takeoffs from a two-footed jumping position should have the feet at hip width or slightly wider; conversely, when landing, land with both feet closer to shoulder-width distance apart.
- Distribute weight appropriately for different movements; for example, when starting mechanics from a stationary staggered stance, most of the weight should be placed on the lead leg to optimize horizontal force into the ground.
- Maintain proper shin angles, especially during the initial driving strides while accelerating. The intent should be to drive the leg back behind the body and fully extend at the hip, knee, and ankle. A significant part of this technique is to begin with a positive shin angle that is a forward tilting of the lower leg bones. A negative shin angle during initial acceleration indicates that the foot is too far in front of the body, which would create excessive braking forces during footstrike.
Because there are many important components to a typical practice or competition, it can be very challenging to coach such technical aspects after the warm-up is over, so the warm-up itself offers an excellent opportunity to refine body positioning and posture as it relates to athletic performance.
There are certain challenges and considerations that coaches must address with respect to the warm-up. For example, while it would be ideal to allow 10 to 20 minutes for the warm-up period, time constraints may reduce that period significantly in real life. Coaches often only have only 5 or 10 minutes of quality work to prepare the athletes for the ensuing practice, so they must consider several factors when determining the length of the warm-up. For example, if the agility session for the day is going to be of higher intensity, the coach may want to allow a slightly longer warm-up period to make sure that the athletes are adequately prepared for the session. It has been well established that a subnormal body temperature has an adverse effect on neuromuscular performance. In colder weather, it would therefore be prudent to minimize the time between warm-up and the agility session so that athletes will not cool down before the session begins. Conversely, research also reveals that heat stress reduces a person's ability to achieve maximal metabolic rates during exercise and that, during exercise-induced heat stress, competing metabolic and thermoregulatory demands for blood flow make it difficult to maintain an adequate cardiac output. Therefore, in warmer, more humid weather, the duration and intensity of the warm-up should be shortened to minimize the risk of fatigue and heat-related illness. Another potential obstacle during warm-ups may be space limitations. If this is an issue, it is advisable to have back-up exercises and movements that can be performed easily and safely in a small area.
Proper warm-ups should be taught in a systematic fashion. The following guidelines should be adhered to during all warm-ups.
- Begin with simple movements such as marching. Once the athletes demonstrate a level of proficiency with the marches, progress to skipping; as these simple movements become less difficult, progress the athlete to more complex movements and variations.
- Make sure that the movements are performed slowly enough to achieve an acceptable level of performance before attempting to go to full speed.
- Rehearse bilateral work before incorporating unilateral skills, especially with takeoffs and landings. Training ladders may be useful to help improve rhythm, timing, and coordination. The literature supports closed skill movements in various directions over prearranged distances to build correct movement patterns in novice athletes. After a high level of technical proficiency is attained, these tools may no longer be as beneficial from a skill development standpoint. However, they can certainly be included as part of a dynamic warm-up because they will prepare the body physiologically (e.g., increased heart rate, breathing rate, perspiration rate, etc.).
- Perform unloaded or bodyweight movements with proper movement patterns before considering adding some form of external resistance (e.g., resistance tubing). Training sessions should be performed no later than 15 minutes after termination of the warm-up. It has been demonstrated that the positive effects of warm-up begin to dissipate after 15 minutes; ideally, therefore, the athletes should be ready to practice as soon as the warm-up ends.
- Be sure to keep the warm-up appropriate to the fitness levels of the participants. The warm-up should prepare the individuals for training and/or competition without being so stressful as to cause fatigue.