Best Practices for Technical Video Analysis
By Alex Johansson & David Ramos
Technical video analysis enables coaches to show players a new perspective on their strokes & movement etc. Since 90% of communication is visual, this is a powerful tool.
Selecting a video app
Selecting the best video analysis program depends on each coach’s comfort with technology and coaching style. Whichever video capture method a coach chooses should have a comfortable interface and be quick to use. Both new and established smartphone apps can fulfill these needs; the app should allow video to be saved to the coach’s phone as to not be locked up in the provider's cloud unless desired. Additionally, any program that has a slow-motion filming mode is preferable, because standard filming options often lose detail when slowed down. For in depth article on the different apps, see the article " Video Analysis Apps " by Doug Eng
These are all good apps when wanting to go beyond the phone camera and it's markup features.
Capturing clear and useful video
After choosing a video filming app, a coach should keep in mind some basic techniques in order to capture clear video. Controlling the lighting and contrast in a video allows for easier viewing and analysis of video. Outdoor lighting is optimal, but indoor filming is fine as long as the player is in focus. Make sure to have the sun at your back when filming outdoors.
To ensure that the player is in focus most smartphone apps allow users to tap the player to calibrate the camera’s focus given the lighting. Additionally, the steadier the camera stays during filming, the clearer and smoother the video. For best effect, a camera can be mounted to a coach’s teaching cart using an affordable bicycle handlebar mount.
Try positioning the camera so that the video background behind the player is a solid color like the court or a fence with windscreen. Any fine movement, analytical text, drawings, or calculations will stand out more on these simple backgrounds. Stay away from using zoom as much as possible as it reduces the resolution. If you need the ability to zoom you may need a video camera with good optical zoom.
When filming on court, the video’s perspective greatly impacts the message of the video. Make sure to fill the frame with the subject while capturing the entire body and stroke.
Angles
Video analysis allows the coach to frame a shot or use a specific still to visually reinforce a concept for a student. Certain angles can exaggerate or minimize aspects of a stroke. Neutral camera angles are best for analyzing the development and progression of strokes over time. For groundstrokes film directly from the side and back. To just show a groundstroke for one-time analysis, a dynamic 45-degree angle from the front and side is preferable.
Effective serve filming angles include directly sideways and angled from behind (facing the middle of the target service box). In general, choose to film from a perspective that clearly shows the issue or desired improvement. Experimentation with different angles is key to finding the most effective perspective for a particular student.
The Tools of Analysis
The effectiveness of an analysis comes down to drawing your students attention to the most relevant cues. The use of the following tools and techniques will allow you to discover more as a coach and share more concise and specific feedback to your player:
Play Back Speed
Play your recorded clips back in different speeds. During real time listen for quality of contact and you initial thoughts. Then use slow-motion and frame advance to view with more detail.
Use of Key Positions
Break each motion into the functional checkpoints within a motion that define the quality of the movement.
Zoom
Zoom into the details within the video to narrow the focus of the athlete and see.
Drawing Tools
Use circles, boxes and lines as well as angle tools and other measuring devices to clarify your analysis.
Voice Over
Use the review feature to record your voice as well as all the screen motion and graphics to deliver a complete analysis Side by Side
Side By Side
Try different side by side comparisons. Be sure to use video of the same orientation and frame rate.
Athlete vs themselves (same stroke different views or same stroke before and after).
Athlete vs a model performer with solid technique (this does not have to be top pro) Use Build a Reference Clip library.
Sometimes several angles at once for view of different perspectives can be helpful (use two or more cameras filming the same stroke at the same time).
Take video of players of various ages and stages of development to use in your reference clip library. Comparing players with someone in their own club can sometimes be more effective than top pros. One can use Coaches eye to download clips from YouTube.
Screen shots
Screen shots are one of the most important and effective uses of video analysis. A coach may repeatedly view a video to observe how a stroke’s disparate parts come together as one motion. However, for a student to implement changes it is more useful to focus on simple still images. These static images act as checkpoints that students can keep in mind while executing their strokes. To make screen shots even more powerful, a coach can use markup tools and side by side comparisons to give students more information. In the end the moving image is ideal for a coach’s analysis and the still picture is perfect for a player’s action.
This is using the screen shot feature and built in markup tools on an iPhone
Analyzing and reviewing the video:
Instead of players waiting while the coach analyzes the video, the delivery of video and analysis to the student should be simple and fast. Involving a player in the process of analyzing video empowers the player and takes pressure off of the coach. Students typically watch their video carefully, and often times the coach’s only job is to direct the student’s focus. Other times the coach may choose not to say anything at all so as not to get in the way of the student. When the student requires guidance in analyzing the video, the coach can help by showing the player a new perspective. A coach should not go beyond his or her comfort levels with the analysis of the video; however, make sure that that the analysis goes beyond just pointing out the differences between students and professional players. Simply comparing the outcomes of a stroke’s appearance is not that useful for most players. A more effective method of analysis, used by video analysis experts for professional players and Tennis Federations, is to present a few positives and one thing to correct. The inclusion of some positives reinforces the things the student does well, and the correction provides an opportunity for intrinsic motivation in the player. Effective video analysis is not a way of showing players what is wrong but a way of providing actionable improvement opportunities.
Authors:
Alex Johansson
Director New England Academy of Tennis | Founder of hoplu.com & TennisFilm.com
Dave Ramos
USTA Player Development: Senior Manager of Coaching Education and Performance