Warm-up and Static Stretching Is a Common Routine Prior to Performance:
Stretching as part of warm up is commonly integrated as part of the pre-competition routine for competitive athletes and recreational fitness participants in order to reduce injury and improve muscular performance. Previous recent research ¹ suggests that acute stretching before maximal muscular performance may hinder the ability of the muscle to produce force.  Two theories to explain this include mechanical factors such as reduced stiffness on the musculotendinous unit and/or neural factors such as altered motor control or a greater autogenic inhibition.¹ However, this study investigated stretching volume, rest interval, and stretching method effects on the 1 Repetition Max bench press in resistance trained collegiate football players.

It was thought that static stretching would be detrimental to 1 RM performance. The investigators proposed that high volume static stretching (HVSS) and high volume Proprioceptive Neuromuscular Facilitation (HVPNF) stretching would have a significant detrimental effect on 1 RM bench press because of repeated high volume placed on the muscle.  A within–subject randomized repeated measures design was used. Fifteen athletes completed 5 different stretching protocols integrated with a 1RM dynamic warm-up routine followed by 1RM bench press testing in randomly assigned order.

5 Stretching Protocols:
The protocols included a) non-stretching (NS), b) low-volume  PNF stretching (LVPNFS), c) HVPNFS, d) low-volume static stretching (LVSS), and e) HVSS. The two stretches selected were the chest/shoulder partner stretch, and the overhead triceps partner stretch.

Types of Subjects and Conditions Important for Study Selection:
All of the subjects were injury free and able to perform stretching exercises and the 1RM bench press test without pain.  Furthermore none of the subjects had taken creatine or other performance-enhancing substances within the previous 90 days. Subjects refrained from vigorous upper body exercise for 48 hours before each testing session. Anthropometric measurements were taken before testing and the 3 site skin folds for body composition (chest, abdomen, thigh) and body weight to the nearest 10th of a kilogram.  The strength testing protocol was the American College of Sports Medicine guidelines for the Bench Press 1 RM.  The subjects assumed a supine position on a bench with the feet flat on the ground, the grip on the bar at slightly wider than shoulder width and the bar lowered to the chest in a smooth, controlled manner and lifted to a maximal upper limb length.

Results:
One way ANOVA analysis showed that there was no significant effect of any of the 5 stretching treatments on the 1 RM bench press performance.  Furthermore, repeated measures ANOVA revealed no significant differences among the testing days which indicates there was no testing order effects.  So, while the investigators expected a detrimental effect on the 1 RM results, no negative effects were determined. However, the rest interval after the stretching session and prior to the initial 1 RM attempt was 5 minutes.  This time interval may have been sufficient time to mitigate the effects of the stretching protocols on muscular performance.  This was consistent with the findings reported by Torres et al. ² on upper body performance by collegiate track throwers with 5 minutes of rest after stretching. 

Discussion:
This study and most comparative studies had trained collegiate athletes as subjects that performed regular stretching as part of the training warm-up routine and suggests that they have developed an adaptation of recovering from altered elastic properties of the musculotendinous unit within the 5 minutes of rest. Also, previous studies that reported decrements in performance was mostly studied in the lower body (Achilles tendons, hamstrings, calves) and suggest that acute stretching in the upper body may respond differently to acute stretching in the lower body. 

Student Questions:
1) Do you see how trained athletes versus untrained subjects might get different results?  There seems to be an adaptation to a set routine and regular warm-up and strength training.
2) What does the Law of Specificity have to do with this?
3) If you were conducting a follow up study, what would you alter to test subjects and get different results?

¹Zachary D. Molacek, Donovan S. Conley, Tammy K. Evetovich, and Kristi R. Hinnerichs. Effects of Low-and High-volume Stretching on Bench Press Performance In Collegiate Football Players. Journal of Strength and Conditioning Research 24:711-716, 2010.
²Torres, EM, Kraemer, WJ, Vingren, JL, Volek, JS, Hatfield, DL, Spiering, BA, Ho,JY, Fragala, MS, Thomas, GA, Anderson, JM, Hakkinen, K, and Maresh, CM. Effects of stretching on upper-body muscular performance. Journal of Strength and Conditioning Research 22:1279-1285,2008.

Weight rooms continue to add new machines and tools to allow exercisers to work out in a variety of ways. Most weight rooms have many different machines and exercises that can work the upper body. The bench press, works the pectoralis major, triceps barchii and anterior deltoid, with stabilization by the medial deltoid.  A variety of equipment and a large number of options such as a free weight bench press, seated chest press, or Smith Machine bench press can be used to perform a bench press exercise.

But how do these machines and exercises fare in regards to last week’s blog “Training on Unstable Surfaces: Superior to Traditional Strength Training?” Many experienced lifters accept the free-weight bench press as the ideal method for maximal upper body strength gain. The Smith Machine, such as the one in the picture above¹, offers a safer and more controlled means of training the same muscles for inexperienced lifters.

The Smith Machine is a weight lifting rack with fixed rails that the bar moves along. Most can be used for a variety of exercises by moving a bench into or out of the rack. In addition, many have catch points for the bar to stop at or rest on to increase safety.

But what happens to muscle activation during lifts on the Smith Machine versus the free weight bench press? A recent study² found that there were no significant differences in muscle activation of the pectoralis major or anterior deltoid for experienced and non-experienced lifters. The study looked at any a variety of loads (70% 1RM & 90% 1RM) for both groups. There was a significant difference in muscle activation by the medial deltoid. The free weight bench press required more activation of the medial deltoid. This muscle helps stabilize the shoulder joint during the resisted phase of the free weight bench press.

Since the Smith Machine bench press required less stabilization, you might think that this would allow for greater loads to be used. This was not found in the study. “It may be that the unnatural bar path of the smith machine forces the subjects to press in an unnatural linear path instead of the reverse ‘C’ observed during free weight bench press, subsequently hindering optimal force production.”

This confirms that both exercises are good options in the weight room, but depend on the goal of the exerciser. These results suggest that the free weight bench press may lead to increased requirement for stabilization about the shoulder joint from muscles such as the medial deltoid. Exercisers should determine if this is an area in need of development when choosing an exercise and working towards their training goal. 

Activities such as basketball, baseball, tennis, racquetball, hockey or volleyball require movement and stability by the glenohumeral joint. If preparing for these activities then the free weight bench press might be the best exercise. But as with any exercise, machine or tool in the weight room, it all goes back to the purpose or goal.

¹Photo permission from: Free Motion Fitness, www.freemotionfitness.com. 03/25/10.

²Schick, EE, Coburn, JW, Brown, LE, Judelson, DA, Khamoui, AV, Tran, TT, and Uribe, BP. A comparison of muscle activation between a Smith machine and free weight bench press. J Strength Cond Res 24(3): 779-784, 2010.