# The Impact of Draw Weight on Archers' Posture and Injury Risk Through Motion Capture Analysis
## 2 Methods
### Operational Tasks  
Archers were equipped with standard gear: an arm guard, a split finger tab, and three different bare recurve bows (shown in Figure 1). The bows had varying draw weights  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Subjects** & **Number** & **Body Mass (kg)** & **Body Height (cm)** \\ \hline Females & 6 & 66.2 \(\pm\) 17.2 & 162.5 \(\pm\) 7.5 \\ \hline Males & 7 & 75.4 \(\pm\) 20.4 & 174.7 \(\pm\) 9.6 \\ \hline \hline \end{tabular}
\end{table}
Table 1: The body weight and body height for females and males are presented in the format of Mean \(\pm\) Standard Deviation.  
(20 lbs, 25 lbs, and 32 lbs), but all maintained the industry standard 28-inch draw length. The bows themselves weighed 9 Newtons (N), 11 N, and 25 N, respectively.  
Each participant completed a series of shooting trials, where they shot five arrows at specific target height, distances, and bow draw weights. They shot at two distances: 10 yards (close target--C) and 15 yards (far target--F). The target center was positioned 140 cm from the floor. In total, each participant shot 30 unique arrows: 5 arrows with each of the three bows at both close and far distances. This variation in shooting conditions allows for a more comprehensive analysis of archery form and biomechanics. A GoPro camera (HERO8) filmed each combination listed below for later analysis.  
Task#1: Shot five arrows with a 20-lb bow at 10 yards (close distance).  
Task#2: Shot five arrows with a 20-lb bow at 15 yards (far distance).  
Task#3: Shot five arrows with a 25-lb bow at 10 yards (close distance).  
Task#4: Shot five arrows with a 25-lb bow at 15 yards (far distance).  
Task#5: Shot five arrows with a 32-lb bow at 10 yards (close distance).  
Task#6: Shot five arrows with a 32-lb bow at 15 yards (far distance).  
This study focused on target archery using recurve bows, adhering to USA Archery guidelines. All participants, regardless of prior archery experience, were guided through the shooting sequence and encouraged to perform to their best ability. Before each shooting session and when switching bows, participants were given ample time to warm up until they felt comfortable proceeding. A certified archery coach ensured range safety and provided instruction on safe and methodical shooting techniques beforehand. To maintain consistency, guidance was limited to a few fundamental steps: stance, arrow knocking, draw, anchor point, aiming, and release. The coach instructed participants to use the 3-under finger shooting technique (where the index, middle, and ring fingers grip the string below the neck) and to anchor the bow hand at the corner of the mouth.  
The experiment began with participants shooting five arrows at the close target (10 yards) using the lightest draw weight bow (20 lbs). This constituted one combination. Participants then repeated the combination at the far target (15 yards) before moving on to the 25-lb bow and repeating the entire close-far target sequence. Finally, they followed the same process with the heaviest bow (32 lbs). This structured approach allowed participants to gradually adapt to increasing draw weight and target distance.  
Figure 1: (**a**) Three bows with different draw weights 20 lbs (right), 25 lbs (middle) and 32 lbs (left). (**b**) Targets at different distances.