The comparison between the one and two-handed backhand techniques using 3D

analysis software

Introduction

‘Efficient force to create maximum ball velocity is produced through a coordinated activation of the segments of the body, starting with ground reaction force of the feet on the ground, and ending with acceleration of the racquet through the ball’ (Haake and Coe 2000). In order for any ground stroke to work it must have every part of the body working to execute it, from the feet to the shoulders. Many players assume that the only real difference between the one and two-handed backhands are, that the dominant arm has to produce more force with the one-handed backhand as the non-dominant arm is there just to balance the racket. Machar and Elliott states that five segmental rotations are involved in the SH backhand, while the DH required the co-ordination of hip rotation followed by the rotation of the trunk-limb-racquet as a unit. The two-handed backhand in essence is less complex to hit than a one-handed backhand as the use of both arms means there’s less for the rest of the body to lose balance.

Obviously there will be differences among individual players, but from previous research carried on the subject, most would agree that the two-handed backhand will use less degrees of motion due to less segments rotating. However work carried out by Coaching and Sport Science Review found that sequential coordination of four to five body segments is also required for the two-handed stroke: hip rotation, shoulder rotation and varying degrees of motion about both shoulders, elbows and wrists contribute to the production of force during a shot (Coaching and Sport Science Review). The shots produced by the one-handed backhand are more spin generated, which means more looped shots. The ball flight would begin very steeply, and will finish with more of a decent than a two-handed backhand shot. ‘The two-handed backhand is characterized by a straighter backswing and less looped motion due to the constraints of the non-dominant hand in holding the racquet’ (Pluim and Safran 2004).

‘The shoulders move in synchrony with trunk rotation’ (Pluim and Safran 2004). A skilled two-handed backhand would then essentially be a weight shift with hip rotation, followed by trunk rotation with the arms and racquet rotation with the trunk (Knudson 2006). Shoulder rotation is incredibly important in generating high racket head speeds as part of the kinetic chain. Knudson 2006 states that the two-handed backhand has a reduced range of motion because both arms are used and tend to be slightly bent. Another important segment rotation to consider is that of the trunk, without this part of the body functioning properly the rest of the stroke will suffer. ‘Trunk rotation is more pronounced in the two-handed backhand because the back shoulder must rotate more completely with the follow-through’ (Pluim and Safran 2004). Wang et al found that the major movement of the trunk during the acceleration phase of single handed backhands was left bending for balancing the body and enlarging the space of the forward swing. In the follow-through phase, the major movements of the trunk were right bending and right rotation (Wang et al).

The next stage in the upper body segments is the shoulders; this is where the two techniques differ. This is mainly due to the fact that the non-dominant arm is either contributing to the force of the shot for the two-handed backhand, whereas the one-handed backhand’s non-dominant arm is there for support. ‘The follow-through on the two-handed backhand is more over the shoulder than the one-handed backhand’ (Pluim and Safran 2004). Wang et al found that the major movement of the shoulder joint was abduction for speeding up the racket. The major movements of the shoulder joint were flexion and abduction, and the major movement of the forearm was supination for controlling the rotation of ball.

Another important body segment for the backhand stroke is the elbow. The elbow is more known as an injury that a segment to tennis players. The dominant elbow is more flexed in the one-handed than the two-handed technique. The non-dominant elbow in both the one-handed and two-handed backhand is very much important to the completion of the shot, with both flexing to maintain the balance of the arms. Wang et al noted that in the one-handed backhand, the elbow began to extend from the initial acceleration and reached the maximum value immediately after impact. Wang et al also stated that the elbow joint was kept near full extension position throughout the follow-through phase.

The final segment in the chain is the wrist segment, which is a key factor in determining how much spin can be generated. The wrists in the two-handed backhand tend to be flexed as it assists the dominant wrist, whereas the one-handed backhand doesn’t tend to flex as much. Wang et al found that in single-handed backhands the wrist also extended and reached the maximum in the later acceleration before impact. Then the wrist movement changed to flexion and radial/ulnar deviation in the order to control the direction of the racket for the proper impact. He also found that after impact, the wrist continued its extension in order to control the direction of the ball in the follow-through phase.

‘The shorter hitting radius of the two-handed stroke provides for greater angular velocities of the racket head at impact, and thus comparable linear velocities at the impact position. A reduction of the hitting radius is further magnified in two-handed players that incorporate the use of more elbows and wrists (ie. Venus or Serena Williams) during stroke production’ (Coaching and Sport Science Review).

Marchar and Elliott reported the two-handed backhand producing greater ball velocities, top spin and disguise when compared to the one-handed stroke. They also reported that the two-handed backhand may be used independently to increase racquet speed and manipulate the orientation and trajectory of the swing prior to impact.

The purpose of the study is to analyse the rotations of the elbow, shoulder and trunk segments for both one-handed and two-handed backhands using 3D analysis. The comparison would not only be made by the two techniques, but also comparing the down the line shot, against the cross court shot. The areas of key interest were in the preparation, the impact, and the follow-through phases.

Method

Two students from the University of Central Lancashire were selected for the investigation. Participant 1 was aged 20, height 195cm, weight 70kg. Participant 2 was aged 21, height 186cm, weight 78kg. Both had read the participant information sheet, and had signed both informed consent and par Q forms. Both play regularly for the university.

The segments included in the investigation were the elbow, shoulder and trunk. The segments

were established by using reflective landmarks on their upper extremities. The segments

would be constructed using landmarks on the body.

They were asked to complete a brief five minute warm up so that their blood flow was

circulating and that themselves were more prepared.

Before the participants would begin the experiment, the 3D cameras had to be calibrated.

Once the calibration had been completed, a static capture had to be taken for both the

participants.

Figure 1 – Static image for participant 1

Once a static image had been taken, the participants had some practice shots for both down the line, and cross court shots. The practice sessions were used in order to find their ideal hitting range, the feeds was done by the investigator for both practice and real sessions.

Both participants hit four shots straight towards the target to replicate a down the line motion, with the other four shots hit across the body to replicate a cross court motion.

Figure 2 – Static image for participant 2

Figure 3 – Shows the 3D camera set up, the position of the participant. The blue lines show the direction of the down the line shots, and the red line show the direction of the cross court shots.

Figure 3 – Shows the 3D camera set up, the position of the participant. The blue lines show the direction of the down the line shots, and the red line show the direction of the cross court shots.

The capture of data was recorded using the Qualisys Track Manager for calibration, static and dynamic trials. The calibration was recorded for 40 seconds, with the static only required one second. The dynamic trials were recorded for a total of 15 seconds for each type of shot. The saved files were given their landmark names, saved and exported to the Visual 3D software, where the models were created and the results could be put into tables.

Results

Figure 4 – Results from both participants comparing down the line (red line) against cross court (black line) for the elbow segment. The grey line shows the time that the participant struck the ball.

Figure 5 – Results from both participants comparing down the line (red line) against cross court (black line) for the shoulder segment. The grey line shows the time that the participant struck the ball.

Figure 6 – Results from both participants comparing down the line (red line) against cross court (black line) for the trunk segment. The grey line shows the time that the participant struck the ball.

Figure 7 – Results from both participants comparing two-handed (red line) against one-handed (black line) for cross court shots for the elbow segment. The grey line shows the time that the participant struck the ball.

Figure 8 – Results from both participants comparing two-handed (red line) against one-handed (black line) for down the line shots for the elbow segment. The grey line shows the time that the participant struck the ball.

Figure 9 – Results from both participants comparing two-handed (red line) against one-handed (black line) for cross court shots for the shoulder segment. The grey line shows the time that the participant struck the ball.

Figure 10 – Results from both participants comparing two-handed (red line) against one-handed (black line) for down the line shots for the shoulder segment. The grey line shows the time that the participant struck the ball.

Figure 11 – Results from both participants comparing two-handed (red line) against one-handed (black line) for cross court shots for the trunk segment. The grey line shows the time that the participant struck the ball.

Discussion

Figure 12 – Results from both participants comparing two-handed (red line) against one-handed (black line) for down the line for the trunk segment. The grey line shows the time that the participant struck the ball.

There were three stages to every shot that was taken in the experiment; they were the preparation

phase, the impact, and the follow-through phase. The grey vertical line in every graph shows the

impact of the ball by the participant. There were in total for each participant eight balls hit, four balls

for the down the line shots, and four balls for the cross court shots. The grey, red and black lines

show the average for each condition. The start of the graph is the preparation phase of the shot,

with the end of the graph showing the finish of the follow through.

Figure 4 shows the results from both participants comparing down the line (red line) against cross

court (black line) for the elbow segment on the same graph. At the start of the graph (preparation

phase) both down the line and cross court strokes are very similar. However just before the impact

phase the cross court shots starts to extend more than the down the line shot only by a few degrees.

The cross court shot remains more extended until mid-way through the follow-through phase. The

overall look of the elbow segment is that the down the line shot rotates more than the cross court

shot. The black line is more horizontal, especially during the follow-through phase, showing less

rotation in this segment.

Figure 5 shows results from both participants comparing down the line (red line) against cross court

(black line) for the shoulder segment. At the start of the graph (preparation phase) the down the line

shot is showing more degrees of motion than the cross court shot. By the impact phase of the stroke

the down the line shot is extending the shoulder more than the cross court shot. By the middle of

the follow-through phase both shots are producing the same degrees of motion, however by the end

of the phase, the down the line shot is producing greater extension than the cross court shot. The

red line itself shows more of a rapid vertical motion during the preparation and impact phases, and

gradually becomes more horizontal during the follow-through phase. Where as the black line shows

more of a steady vertical assent during the preparation and impact phases, and more of a horizontal

direction during the finish of the follow through phase.

Figure 6 shows the results from both participants comparing down the line (red line) against cross

court (black line) for the trunk segment. Through all three phases both shots are very similar. At the

preparation phase both shots are virtually identical, only until the impact phase does the cross court

shot extend slightly more than the down the line shot. This few degrees of difference remain

through-out the follow-through phase, and only until the very end of this phase is there a slight

variation. Both lines show a rapid decent mid-way through the preparation phase until mid-way

through the follow-through phase where it becomes more horizontal.

Figure 7 shows the results for the cross court shot comparing the one-handed backhand (black line)

against the two-handed backhand (red line) for the elbow segment. The one-handed backhand

shows more of a horizontal start of the preparation phase, then just before and during the impact

phase there is a rapid decent indicating extension of the elbow, until the very end of the follow-

through phase where the line becomes more horizontal again. The two-handed shot is showing the

opposite results as the red line is producing a high vertical line indicating flexion, all the way to the

impact phase. After that phase and through-out the follow-through phase it is showing a showing a

good horizontal line, meaning there is not as much rotation through-out this phase.

Figure 8 shows the results for the down the line shot comparing the one-handed backhand (black

line) against the two-handed backhand (red line) for the elbow segment. The results show a

significant difference between the two techniques in how mow much rotation is being applied in this

segment. The one-handed backhand shows more extension through-out the impact and follow-

through phases and the two-handed backhand shows flexion in the preparation phase. The main

difference between the two handed backhand in figure 7 and 8 is that there is more of a decent

showing greater extension in figure 8 compared to figure 7.

Figure 9 shows the results for the cross court shot comparing the one-handed backhand (black line)

against the two-handed backhand (red line) for the shoulder segment. The red line travels vertically

up the graph during the preparation, impact, and half way during the follow-through, before ending

the final phase more horizontally. This would indicate that the shoulder segment for the cross court

is showing great extension through-out the majority of the shot. The two-handed backhand (black

line) shows similar characteristics as the one-handed backhand, showing extension through-out the

shot, especially rapid extension from the beginning to the middle of the follow-through phase.

Figure 10 shows the results for the down the line shot comparing the one-handed backhand (black

line) against the two-handed backhand (red line) for the shoulder segment. The results are similar as

figure 9 as the both techniques extend through-out the impact to the follow phases. The one-

handed backhand (red line) shows more rapid extension through the impact and half way of the

follow-through phases, and then shows less rotation for the rest of the final phase. The two-handed

backhand (black line) shows similar results as the one-handed technique, except fewer degrees of

motion and extending for longer through the middle to the end of the follow-through phase.

Figure 11 shows the results for the cross court shot comparing the one-handed backhand (black line)

against the two-handed backhand (red line) for the trunk segment. Both techniques begin showing

the same degrees of motion, the one-handed backhand shows a steady line until the impact phase

where it rapidly descends until the middle of the follow-through phase indicating massive extension.

Then at the end of the final phase it shows a slight vertical incline, presenting minor flexion. The two-

handed backhand extends mid-way through the preparation phase, until the beginning of the follow-

though phase, where the segment is extending far less, showing less degrees of motion.

Figure 12 shows the results for the down the line shot comparing the one-handed backhand (black

line) against the two-handed backhand (red line) for the trunk segment. The results show similar

characteristics as figure 11, both start the preparation on the same degrees of motion, with the lines

for both techniques showing the same pattern through-out the impact and the follow-through

phases. The major differences with these results are that during the beginning of the preparation

phase the two-handed backhand shows minor flexion, and the one-handed backhand not showing

any real flexion towards the end of the follow-through phase.

References

Coaching & sport science review. International Tennis Federation.

Haake, S.J and Coe, A.O. (2000). Tennis Science and Technology. Blackwell Science. P 355-

361.

Kibler, W.B. (1995). Biomechanical Analysis of the Shoulder During Tennis Activities. Clin Sports Med, vol. 14. P 79-86.

Knudson, D. (2006). Biomechanical Principles of Tennis Technique. Racquet Tech

publishing. P 99-104.

Machar, R. (2003). The Backhand – Which one (or two) to use? The university of Western

Australia, Nedlands, Western Australia. P1-4

Machar, R and Elliott, B. The One- and Two-handed Backhands in Tennis. Sports

Biomechanics. Vol. 1, No. 1. P 47-68.

Miller, S and Davies, J.C. (2007). Tennis and Science & Technology 3. Internation Tennis

Federation. P 185-193

Pluim, B and Safran, M. (2004). From Breakpoint to Advantage. Racquet Tech Publishing. P

12-15.

Schonborn, R. (1999). Advanced Techniques for Competitive Tennis. Meyer and Meyer, Aachen Germany. P 11-73.

Wang, H.L, Taiwan, H.W, Su. F.C. Lo, C and Shan, K. Kinematics of Upper Limb and Trunk

In Tennis Players Using Single Handed Backhand Strokes.

Wu, S.K. Gross, M. Prentice, W.E and Yu, B. (2001) Comparison of Ball-and-Racquet

Impact Force Between Two Tennis Backhand Stroke Techniques. Journal or Orthopaedic &

Sports Physical Therapy. Vol. 31, No. 5. P247-254.