Lecture on Speed and Reactive Strength Index (RSI)

Key Concept: Bouncy Feet for Speed

• Fast athletes possess "bouncy" feet that absorb and release forces rapidly.
• Speed is not merely about weight lifting or improved running technique.
• Emphasizes importance of 105 RSI test in evaluating foot reactivity and speed potential.

Reactive Strength Index (RSI)

• RSI Definition: Measures feet's ability to absorb and release force quickly.
• 105 RSI Test:
  • Consists of 1 squat jump followed by 10 pogo hops.
  • Score calculated by air time divided by ground contact time.
  • Scores range from 1.0 to 4.0; 2.5 is good, 3.0+ is excellent.

Importance of High RSI Scores

• Higher RSI scores correlate with faster sprint times.
• Example score comparisons:
  • Low RSI scores (e.g., 1.73) correlate with slower 100m times (e.g., 14.4s).
  • High RSI scores (e.g., 3.77) correlate with faster 100m times (e.g., 10.5s).
• Correlation, not causation: High RSI doesn't guarantee speed.

Developing Bouncy Feet

• Background in martial arts, gymnastics, or ballet often leads to higher RSI scores.
• Low-intensity stress on the feet, often achieved through barefoot activities, is beneficial.
• Example athletes with high RSI scores due to such backgrounds include Evan (RSI 3.77) and Maria (RSI 2.97).

Role of Footwear

• Traditional sneakers provide excessive support, limiting foot muscle engagement.
• Barefoot-style shoes recommended for strengthening feet through everyday activity.

The Spring Club

• An international club offering coaching to enhance speed through online and in-person sessions.
• Focused on improving athletes' RSI scores and overall speed.
• Led by experienced coaches, including Olympic-level educators.
• Opportunities for athletes to win prizes by participating in RSI testing.

Case Studies

• Highlighting athletes from various backgrounds and their RSI scores:
  • Steven Sashin (Master’s All-American Sprinter, Score 2.47)
  • Matus BU (Retired Olympian, Score 3.03)
  • Norris Cole (NBA Champion, Score 2.82)

Conclusion

• Encouragement to start assessing and improving RSI scores.
• Suggestion to engage children in activities promoting foot strength and agility.
• Ongoing effort in the Spring Club to gather data and support athletes globally.