A common freestyle technique misconception is that it is effective for a swimmer to complete the arm entry parallel to the surface, as shown in Figure 1. Unfortunately, a swimmer with a conventional, parallel entry wastes time submerging the arm to a position where propulsion can begin. In contrast, an unconventional arm entry with a downward angle minimizes wasted time and immediately positions the arm to begin generating propulsion.
Figure 1. Triathletes (and competitive swimmers) typically complete the arm entry with the arm parallel to the surface.
Conventional Arm Entry Limits Performance
Triathletes (as well as competitive swimmers) are usually instructed to complete the arm entry with the arm parallel to the surface and level with the shoulder. Accompanying instructions are often to “stretch,” “reach,” and “glide.” The conventional, parallel entry has three substantial limiting factors:
1) wasted time before propulsion can begin,
2) poor leverage (technically, poor mechanical advantage), and
3) increased shoulder stress.
Research clearly shows that swimmers waste time on the arm entry. One study of university freestylers found that the male swimmers typically completed the arm entry parallel to the surface with the hand level with the shoulder, as shown by the Male position in Figure 2 (Becker & Havriluk, 2014). As a result, the male swimmers wasted over one-tenth of a second before their hands submerged below their shoulders and were in position to generate propulsion (i.e., the Optimal position in Figure 2).
Figure 2. The model shows the position of the arm at the completion of the typical male and female arm entries, as well as the optimal entry.
The female swimmers wasted even more time because they typically completed the entry with the hand above the shoulder, as shown by the Female position in Figure 2. Consequently, the female swimmers wasted more than one-quarter of a second before the arm was in position to generate propulsion.
In a second study with over 100 university freestylers (Havriluk, 2018), the wasted time values were again substantial. Figure 3 shows the average submerged time of the arm for males and females in the 2014 and 2018 studies. The submerged time is divided into non-propulsive (wasted) and propulsive time. The graph shows that wasted time is a substantial proportion of the time that the arm is submerged. The optimal entry position minimizes wasted time.
Figure 3. The graph shows the non-propulsive (wasted) and propulsive time that the arm is underwater on the freestyle stroke cycle for males and females in two studies.
At the completion of a parallel arm entry, the angle at the shoulder is 180 degrees. Leverage is very poor because a swimmer can generate only minimal force to begin the pull. At the completion of an optimal arm entry, the angle at the shoulder is 160 degrees, providing improved leverage and positioning the arm to immediately begin generating propulsion.
Increased Shoulder Stress
Wasted time on the arm entry was previously defined as “exposure time to shoulder stress” (Becker & Havriluk, 2010). The typical arm entry position reduces the space between the bones of the upper arm and shoulder (as shown by the yellow arrow in Figure 4). The reduction in space compresses the soft tissue between the bones, often causing shoulder injury. The optimal arm entry position has more space between the bones for less soft tissue compression.
Figure 4. Arm elevation decreases the space between bones of the upper arm and shoulder.
Unconventional Arm Entry Improves Performance
A swimmer can use critical visual and kinesthetic cues to master an unconventional, but effective arm entry, specifically:
An unconventional arm entry may, at first, feel unnatural. To overcome the unnatural feeling, a swimmer must focus on the cues on many thousands of repetitions.
Figure 5. The model demonstrates an optimal freestyle right arm entry: when the arm straightens, the hand is the deepest part of the arm.
There are a number of benefits to an improved arm entry position:
Swimmers typically complete the arm entry with the arm parallel to the surface. The conventional, parallel arm entry wastes time, has poor leverage, and increases shoulder stress. For an optimal arm entry, the hand angles downward as the arm straightens. The unconventional arm entry minimizes wasted time, improves leverage, and reduces shoulder stress.
Becker, T., & Havriluk, R. (2014). Freestyle arm entry effects on shoulder stress, force generation, and arm synchronization. In B. Mason (Ed.), Proceedings of the XIIth International Symposium on Biomechanics and Medicine in Swimming. Australian Institute of Sport, Canberra.
Becker, T.J., & Havriluk, R. (2010). Quantitative data supplements qualitative evaluation of butterfly swimming. In P-L. Kjendlie, R. K. Stallman, & J. Cabri (Eds.) Biomechanics and Medicine in Swimming XI. Norwegian School of Sport Science, Oslo.
Havriluk, R. (2018). The effect of the freestyle arm entry on exposure time to shoulder stress, the index of coordination, and swimming velocity. Proceedings of the XIIIth International Symposium on Biomechanics and Medicine in Swimming. University of Tsukuba, Japan.
Dr. Rod Havriluk is a sport scientist and consultant who specializes in swimming technique instruction and analysis. His unique strategies provide rapid improvement while avoiding injury. Learn more at the STR website - swimmingtechnology.com or contact Rod through [email protected].