Skeletal and Cardiovascular Systems

CSCS Certified Strength and Conditioning Specialist

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1 Introduction

About the CSCS Exam Structure and Content Breakdown Pass Rates and Scoring How to Use This Guide

2 Exercise Science

Muscular and Neuromuscular Systems Skeletal and Cardiovascular Systems Bioenergetics and Metabolism Biomechanics Physiological Adaptations to Training

3 Sport Psychology & Nutrition

Motivation and Goal Setting Arousal, Anxiety, and Performance Mental Skills and Team Dynamics Macronutrients and Energy Hydration, Timing, and Supplements

4 Exercise Technique

Resistance Training Technique Olympic Lifting Technique Plyometric and Speed Training Flexibility and Warm-up Spotting and Equipment Safety

5 Program Design

Needs Analysis and Training Goals Training Variables Periodization Models Resistance Training Program Design Speed, Agility, and Conditioning Programs

6 Testing, Evaluation & Administration

Pre-Participation Screening Cardiovascular and Body Composition Testing Strength, Power, and Speed Testing Flexibility Assessment Facility Management and Legal Issues

Skeletal and Cardiovascular Systems

Key Takeaways Explain This Topic AI

Bone responds to mechanical stress through remodeling (Wolff's Law)—osteoblasts build bone, osteoclasts resorb bone.

Tendons connect muscle to bone (high tensile strength); ligaments connect bone to bone (provide joint stability).

Cardiac output (Q) = Heart Rate (HR) x Stroke Volume (SV); increases during exercise via both HR and SV.

Blood pressure response: systolic increases with exercise intensity; diastolic remains relatively constant or slightly decreases.

Maximum heart rate can be estimated as 220 - age; however, individual variation is significant.

Last updated: January 2026

Quick Answer: Bones adapt to mechanical loading through remodeling (Wolff's Law), with osteoblasts building and osteoclasts resorbing bone tissue. The cardiovascular system increases cardiac output (Q = HR x SV) during exercise, with typical maximal values around 20-25 L/min in trained athletes. Systolic blood pressure rises with exercise intensity while diastolic remains stable.

• Bone Anatomy and Physiology
• Bone Types

• Bone Type Characteristics Location Examples
• Long bones Longer than wide, shaft (diaphysis) and ends (epiphyses) Femur, humerus, tibia
• Short bones Roughly cube-shaped Carpals, tarsals
• Flat bones Thin, flat, curved Skull, sternum, scapula
• Irregular bones Complex shapes Vertebrae, pelvis
• Sesamoid bones Embedded within tendons Patella
• Bone Composition

• Component Percentage Function
• Mineral (calcium phosphate) ~65% Rigidity, compressive strength
• Organic matrix (collagen) ~35% Flexibility, tensile strength
• Bone Cells

• Cell Type Function Activity
• Osteoblasts Build new bone tissue Bone formation
• Osteoclasts Break down bone tissue Bone resorption
• Osteocytes Maintain bone tissue Mechanosensors
• Wolff's Law and Bone Remodeling

Wolff's Law states that bone adapts to the loads placed upon it:

• Increased loading (weight training) → bone deposition → increased bone density
• Decreased loading (immobilization, bed rest) → bone resorption → decreased bone density
• Bone Remodeling Process
• Osteoclasts resorb old or damaged bone tissue
• Osteoblasts deposit new bone matrix
• Mineralization occurs over several weeks
• Osteocytes maintain the mature bone tissue

Exam Tip: Weight-bearing and resistance exercises are particularly effective for increasing bone mineral density, making them important for osteoporosis prevention.

Factors Affecting Bone Health

• Factor Effect on Bone
• Mechanical loading Increases bone density
• Calcium/Vitamin D intake Supports mineralization
• Hormones (estrogen, testosterone) Promote bone formation
• Age Bone loss accelerates after age 30
• Inactivity Promotes bone resorption
• Connective Tissue
• Tendons

• Property Description
• Function Connect muscle to bone
• Composition Primarily Type I collagen (parallel fibers)
• Strength High tensile strength, low elasticity
• Blood supply Poor (slow healing)
• Adaptation Increases stiffness and cross-sectional area with training
• Ligaments

• Property Description
• Function Connect bone to bone, stabilize joints
• Composition Type I collagen (less organized than tendons)
• Strength Moderate tensile strength, more elastic than tendons
• Blood supply Poor (slow healing)
• Injury risk Sprains from excessive joint motion
• Cartilage

• Type Location Function
• Hyaline Joint surfaces, growth plates Low friction movement
• Fibrocartilage Intervertebral discs, menisci Shock absorption
• Elastic Ear, epiglottis Flexibility

Key Point: Cartilage is avascular (no blood supply) and has very limited healing capacity when damaged.

• Cardiovascular Anatomy
• Heart Structure

The heart has four chambers and functions as two pumps:

• Side Chambers Function
• Right side Right atrium, Right ventricle Pumps deoxygenated blood to lungs
• Left side Left atrium, Left ventricle Pumps oxygenated blood to body
• Heart Valves

• Valve Location Function
• Tricuspid Right atrium → Right ventricle Prevents backflow
• Pulmonary Right ventricle → Pulmonary artery Prevents backflow
• Mitral (Bicuspid) Left atrium → Left ventricle Prevents backflow
• Aortic Left ventricle → Aorta Prevents backflow
• Blood Flow Pathway
• Deoxygenated blood → Superior/Inferior vena cava → Right atrium
• Right atrium → Tricuspid valve → Right ventricle
• Right ventricle → Pulmonary valve → Pulmonary arteries → Lungs
• Oxygenated blood → Pulmonary veins → Left atrium
• Left atrium → Mitral valve → Left ventricle
• Left ventricle → Aortic valve → Aorta → Body
• Cardiac Output

Cardiac Output (Q) is the volume of blood pumped by the heart per minute:

• Formula
• Q = HR x SV

Where:

• Q = Cardiac output (L/min or mL/min)
• HR = Heart rate (beats/min)
• SV = Stroke volume (mL/beat)
• Typical Values

• Population Resting Q Maximal Q Resting SV Maximal SV
• Untrained 5 L/min 15-20 L/min 70 mL 100-120 mL
• Trained 5 L/min 25-35 L/min 90-100 mL 150-200 mL
• Elite endurance 5 L/min 35-40+ L/min 100-120 mL 180-220 mL

Exam Tip: Resting cardiac output is similar in trained and untrained individuals (~5 L/min). The difference is that trained individuals achieve this with lower HR and higher SV (cardiac efficiency).

Factors Affecting Stroke Volume

• Factor Effect
• Preload Greater venous return → greater filling → greater SV (Frank-Starling mechanism)
• Contractility Increased sympathetic stimulation → stronger contraction → greater SV
• Afterload Higher arterial pressure → more resistance → decreased SV
• Training status Endurance training increases SV through cardiac hypertrophy
• Blood Pressure Responses to Exercise

Blood pressure is expressed as systolic/diastolic (mmHg):

Normal Values

• Condition Systolic Diastolic
• Normal rest <120 mmHg <80 mmHg
• Elevated 120-129 mmHg <80 mmHg
• Hypertension Stage 1 130-139 mmHg 80-89 mmHg
• Hypertension Stage 2 >140 mmHg >90 mmHg
• Exercise Blood Pressure Responses

• Exercise Type Systolic Response Diastolic Response
• Aerobic exercise Increases proportionally with intensity Stays same or slightly decreases
• Resistance training Increases significantly (especially during Valsalva) Increases moderately
• Recovery Gradual return to baseline May drop below baseline

Expected systolic values during maximal aerobic exercise:

• Untrained: ~180-200 mmHg
• Trained: ~200-220 mmHg

Warning Sign: Failure of systolic BP to rise with increasing intensity or a drop during exercise may indicate cardiac dysfunction—contraindication for continued exercise.

• Heart Rate
• Maximum Heart Rate Estimation
• Age-predicted HRmax = 220 - age

• Age Estimated HRmax
• 20 200 bpm
• 30 190 bpm
• 40 180 bpm
• 50 170 bpm
• 60 160 bpm

Important: This formula has a standard deviation of approximately 10-12 bpm. Individual variation is significant, and actual HRmax should be determined through maximal testing when precision is needed.

Training Heart Rate Zones

• Zone % HRmax Purpose
• Recovery 50-60% Active recovery, warm-up
• Aerobic base 60-70% Fat oxidation, endurance base
• Aerobic development 70-80% Cardiovascular improvement
• Threshold 80-90% Lactate threshold training
• Anaerobic 90-100% VO2max, speed development
• Oxygen Delivery: The Fick Equation
• VO2 = Q x (a-vO2 difference)

Where:

• VO2 = Oxygen consumption (mL/min or L/min)
• Q = Cardiac output (L/min)
• a-vO2 difference = Arterial minus venous oxygen content (mL O2/L blood)
• Typical Values

• Population Resting a-vO2 diff Maximal a-vO2 diff
• Untrained 5 mL/dL 15 mL/dL
• Trained 5 mL/dL 17-18 mL/dL

Exam Tip: Improvements in VO2max come from increases in both cardiac output (central adaptation) and a-vO2 difference (peripheral adaptation—improved oxygen extraction by muscles).