HLTH2016 – Principles of Strength & Conditioning - Week 9 - Repeat Speed & Endurance

Lecture Outcomes

• Identify contributing factors to aerobic performance.

• Understand and explain training zones

• Understand the concept of MAS and the applications to programming

• Identify and describe contributing factors to RSA

Defining Aerobic Fitness

• Aerobic Fitness

  • Important determinant in sporting success in events where athletes HR is >80%max and lasting in excess of 1hr

  • But not just key in long distance/endurance events;

  • >4min has increased contribution of aerobic metabolism

  • Increased aerobic capacity can improve recovery between and during exercise bouts

• Key definitions:

  • Lactate Threshold – ___

  • Maximal Lactate Steady State – the highest work rate at which blood lactate is elevated above baseline but remains stable

  • Onset Blood Lactate Accumulation – Blood lactate reference value (~4mmol/l)

  • VO2max – Maximal rate of oxygen uptake. Identified as a plateau in VO2 despite increasing work rate

  • Exercise Economy –

Aerobic Performance

• Aerobic Performance components:

  • VO2max (Size of the tank)

  • Lactate Threshold (Number of gears)

  • Exercise economy (Fuel Efficiency)

  • Mechanical Efficiency

  • Neuromuscular Strength/Power

  • Motivation??

    • Are you prepared to hurt?

  • Anaerobic Capacity ??Exercise Intensity Zones

• Zone 1 Training

  • Usually implemented as easy recovery, volume accumulation.

  • Described as a very easy pace/easy to talk

  • Typically endurance athletes spend about 80% of their training at this intensity

• Zone 2 Training

  • Accumulation of zone to help improve economy

  • Described as a comfortably hard pace/ok to talk

• Zone 3 Training

  • Training specific adaptation

Aerobic Performance

• Contribution of different factors at different distances are shown:

  • 800m: High contribution from Anaerobic and VO2max, less from LT and Economy

  • 1500m, 5K, 10K, Marathon: Gradual shift with Marathon relying maximum on Economy, LT and VO2max while having negligible Anaerobic contribution.

Exercise Intensity Zones

• Zone 1

  • Low intensity/easy training

• Zone 2

  • Threshold/steady state training

• Zone 3

  • High intensity/tempo training

s, specific to increasing vV02max, adaptions associated with a-vO2 (mitochondrial and capillary density)

• • Makes up a smaller percentage of total training load

  • Described as hardly comfortable or hard/cannot talk

Metrics for Aerobic Exercise Prescription

Training and Adaptation

• Training intensity and duration influence VO2max, sustainable % VO2max, lactate threshold, and VO2 economy.

• Training status, performance VO2, highest sustainable rate of ATP resynthesis, and mean race pace are also key factors.

• Adequate recovery and chronic adaptive response lead to enhanced functional capacity and performance enhancement.

Fick Equation

• $VO<em>2 = Q \cdot a-vO</em>2$

  • $Q$ = SV * HR (Stroke Volume * Heart Rate)

  • a-vO2 = (Capillaries, Mitochondria)

• Capillaries

  • Increased density improves oxygen diffusion

• Mitochondria

  • Increased Enzyme Activity

• Heart Rate

  • Ejection Fraction

  • Contractility

• Stroke Volume

  • EDV (End-Diastolic Volume)

  • VR (Venous Return)

  • Size

c

Types of Training - LSD

• ~80% of training in Zone 1

• The distribution of training intensity zones varies across different training periods (Preparation, Pre-competition, Competition) and sports (cycling, cross-country skiing, rowing, running, speed skating).

• Seasonal analysis shows variations in training intensity distribution throughout the year.

Types of Training - Interval

• Key components include:

  • Work modality

  • Duration

  • Relief

  • Number of series

  • Time between series

  • Series duration

  • Between-series recovery intensity

Types of Training - Interval

• Factors that influence interval training:

  • Sport demands

  • Long-term adaptations

  • Athlete profile

  • Desired metabolic and/or neuromuscular load of the HIT session

  • Training periodization (Meso/macrocycles, Microcycles, Daily plan)

• Different interval types:

  • Short intervals (<60 s)

  • Long intervals (>60 s)

  • RST (Repeated Sprint Training)

  • SIT (Sprint Interval Training)

Types of Training - Interval W:R Ratio

Types of Training - Interval

Specific Training Adaptations

Repeat Sprint Ability

• In team sports, typically 1-10% of total distance covered is via sprinting

• Sprint = typically ≤10 s and maximal work maintained

• = sprints (≤10 s), interspersed with recovery periods long enough (60–300s) to allow near complete recovery of sprint performance

• = sprints (≤10s) interspersed with brief recovery periods (usually ≤60 seconds).

Repeat Sprint Ability

• Illustrates the difference between intermittent sprints and repeated sprints with regards to work done over sprint number.

Factors influencing RSA

• Initial sprint performance

  • Stride length

  • Stride frequency

• ATP supply

  • Power

• Neural co-ordination

  • Strength

  • Elastic strength

  • Flexibility

• Repeated-sprint ability

Factors influencing RSA - Initial Sprint Performance

• Factors which are critical to sprint speed;

  • ATP-PC synthesis

  • Neuromuscular Coordination

  • Strength/Power

• Onset of fatigue occurs rapidly after the initial sprint = useful in comparing changes in performance across repeated maximal efforts

• $Fatigue Index = 100 − ($

Factors influencing RSA

• Example calculation for Fatigue Index using 30m sprint times.

• Times are 4.56, 4.58, 4.63, 5.02, 5.21, 5.68 seconds for sprints 1 through 6, respectively

• Limitations

  • Can be influenced by a very good first or a very poor last sprint

Factors influencing RSA

• Demonstrates the calculation for a fatigue index based on sprint times.

• $Fatigue\ Index\ ($

• $(\%) = { (4.56 + 4.58 + 4.63 + 5.02 + 5.21 + 5.68) / (4.56 ×6) −1}×100$

• $(\%) = { (29.68) / (27.36) −1}×100$

• $(\%) = {1.08−1}×100$

• $(\%) = 0.08×100$

• $(\%) = 8\%$

Factors influencing RSA - Limitations in Energy Supply

• Intramuscular stores of approximately 80 mmol·kg dry muscle (dm) - 1

• Maximal turnover rates approaching 9 mmol·kg dm- 1·s- 1

• Therefore ~6sec = 35-55% depletion (Bishop, Girard, & Mendez-Villanueva 2011)

Factors influencing RSA - Limitations in Energy Supply

• Anaerobic Glycolysis

  • 40% of energy contribution in 1st sprint

  • 9-10% in last

  • Improving glycolytic power may enhance or inhibit performance…

    • as individuals with the greatest decrements in power output during RSE have been reported to have the greatest glycolytic rate during the first sprint.

    • greater glycolytic rate have also been reported to have a greater initial sprint performance

  • So what's the focus initial speed or maintenance??

Factors influencing RSA - Limitations in Energy Supply

• Oxidative Pathways

  • Little contribution in first sprint; up to 40% in last

  • Athletes may reach during $V̇O2max$ later sprints

  • Improving $V̇O2max$ may enhance aerobic contribution in later sprints & enhance recovery rate between sprints

  • This means smaller fatigue index

Factors influencing RSA - Metabolite Accumulation Acidosis

• Increase in H+ & pH change can influence contractile capacity and inhibit glycolytic rate

• Inorganic Phosphate

  • Rise in inorganic phosphates may limit contractile elements by lowering peak twitch force

  • May impact on calcium release from the sarcoplasmic reticulum and/or myofibrillar calcium sensitivity, which in turn decrease the number of strong binding cross-bridges

Factors influencing RSA - Neural Factors

• Neural Drive

  • Max sprint = _

  • Fatigue = lower EMG activation and amplitude of EMG signals

  • Mild fatigue <__%FI = no change in neural drive

  • Fatigue >__%FI = decline in mechanical performance and the amplitude of EMG signals

Factors influencing RSA - Neural Factors

• Muscle Recruitment Strategies

  • Fatigue has been linked with earlier antagonist activation during cycle sprints

  • Change in fibre type recruitment; greater reliance on type I fibres with fatigue

Training RSA

• Initial sprint performance

  • Stride length

  • Stride frequency

• ATP supply

  • Power

• Neural co-ordination

  • Strength

  • Elastic strength

  • Flexibility

• Repeated-sprint ability

Sprinting Speed

• Sprint Specific Methods – methods in which the athlete is performing the sprint movement pattern

  • Primary – simulating the sprint movement pattern

    • Technique drills (A skips, B skips, bounding, dribbles etc)

    • Stride length + frequency drills

    • Unresisted sprints

  • Secondary – as above but applying overload by reducing or increasing movement speed

    • Resisted sprinting (sleds, bands, hill sprints etc)

    • Heavy >80% bm acceleration

    • Light 5 – 20% bm max velocity

    • Assisted sprinting (decline sprints, bands, pulleys etc)

  • Combined specific – primary and secondary methods

Sprinting Speed

• Non Sprint Specific Methods – methods not involving the sprinting movement, however transfer through training adaptations

  • Strength, power, plyometric training

• Acceleration vs Maximum Velocity

  • Acceleration = ↓ GRF, ↑ GCT, → force vector

  • Max Velocity = ↑ GRF, ↓ GCT, ↑ force vector

Sprinting Speed

• Acceleration Training Prescription Guidelines

  • Distance 10 – 40m / rep

  • Session volume 100 – 300m

  • Intensity > 98%

  • Rest 2 – 7minutes

  • 1 min / 10m

• Max Velocity Training Prescription Guidelines

  • Distance 10 – 30m / rep

  • Session volume 50 – 150m

  • Intensity > 98%

  • Rest 4 – 15 min

  • 2.5 min / 10m

HIIT

Resistance Training

• Unpublished meta-analysis data suggest;

  • Strength and power

  • Potentially doesn’t improve %decrement

  • Looks favourable in reducing total time and RSA best outcomes

• What does this mean?

  • RT can improve the best and early efforts but doesn’t appear helpful in preventing fatigue…