This passage discusses the importance of understanding the concept of power in the context of human performance, particularly in strength and conditioning. It emphasizes the need to correctly define and use the term “power” and highlights that the measurement of power has often been misused or misunderstood. The text suggests that before assessing power, individuals should have a clear understanding of its true definition and the appropriate context in which it should be used.
In the realm of strength and conditioning, power has been measured using various methods and modes, including isokinetic, isoinertial, and ballistic exercises, which involve throwing and jumping activities that allow for acceleration of either the body or external objects through a full range of motion. These assessments aim to describe human muscular performance and provide insights into an individual’s capacity to generate power.
Traditionally, power measurements have often been conducted during maximal efforts over specific durations or distances, such as stair-climbing tests or the Wingate power test. More recently, the focus has shifted to measuring power output during ballistic exercises, where the system’s net power is evaluated. Net power is considered a reflection of the combined efforts of individual joint powers, making it a practical and efficient way to assess power, as it saves time, equipment, and costs compared to direct measurements of individual joint powers.
The passage also underlines that power is a valuable metric for understanding athletic performance, much like sprint times or vertical jump heights. While power is not always a perfect predictor of performance, it provides additional information about the underlying processes contributing to an athlete’s performance. For example, two athletes with the same jump height but differing power outputs can offer insights into how they achieve that jump height.
In summary, the passage stresses the importance of understanding and correctly using the concept of power in strength and conditioning. It provides insights into the various methods of measuring power and how it can offer valuable information about an athlete’s performance, particularly in the context of ballistic exercises.
This passage discusses the definition of the term “power” in the context of strength and conditioning. It begins by highlighting the common misunderstanding and misinterpretation of the term “power” in everyday language. The proper definition of power is established as the rate at which work is done, with the unit of measure for work being the joule and for power being the watt (W), defined as a joule per second. Coaches often refer to athletes as powerful based on the speed of their movements relative to the force they generate or the load they overcome. In this sense, even slower movements involving heavy external loads, like a tackle in football or a weighted jump squat, can be described as powerful because they still exhibit high velocity relative to the force required.
The passage then delves into the mathematical equations associated with power, connecting it to work and time. It demonstrates how power can be expressed as the product of force and velocity, providing a common equation used by strength and conditioning practitioners to calculate power. Additionally, power can be expressed in two ways: mean system power (Pmean) and peak instantaneous system power (Ppeak). Pmean represents the average power over the duration of a movement, while Ppeak is the highest power recorded at a specific point in time during that movement.
The text highlights the trend in strength and conditioning to measure and report Pmean or Ppeak during ballistic assessments such as bench press throws and jumps. It clarifies that these assessments do not measure power itself but rather the Pmean or Ppeak generated during these activities. The passage emphasizes the need to describe the methods of power measurement thoroughly to ensure that results can be correctly interpreted within the appropriate context. Furthermore, it stresses that when measuring power, it is crucial to consider the combination of changes in force and velocity, as power is a mechanical construct that involves both components.
In summary, the passage provides a comprehensive understanding of the definition of power, its mathematical foundations, and the distinctions between Pmean and Ppeak. It also underscores the importance of considering force and velocity when interpreting power measurements in the field of strength and conditioning.
The topic discussed in the provided text is the measurement of power, particularly in the context of strength and conditioning research. The text highlights the different approaches to measuring power in various movements, including discrete movements like squats and bench presses, as well as continuous movements like cycling or rowing. It acknowledges that the measurement of peak power (Ppeak) and mean power (Pmean) during discrete movements may not fully explain or predict overall performance but suggests that changes in Ppeak or Pmean can indicate training adaptations when considered alongside other variables such as force, velocity, or performance metrics like jump height.

The text then delves into the eccentric and concentric phases of the jump. It describes the eccentric phase as the portion of the jump with a negative change of displacement and negative Ppeak and Pmean, starting when force begins to decrease and ending when velocity transitions from negative to positive. This also marks the start of the concentric phase, which subsequently ends at takeoff or when force reaches zero.
The text acknowledges that the actual calculation of power is relatively straightforward when both velocity and force are directly measured, but it hints at the existence of various methods for measuring power, each with its own set of advantages and disadvantages.
In summary, the text primarily focuses on the measurement of power in various movements, using a countermovement jump as an example to illustrate how power is calculated and related to other variables. It highlights the importance of considering changes in power when evaluating training adaptations and mentions the existence of different measurement methods for power, though it does not delve deeply into these methods.
The provided text addresses the critical concepts of validity and reliability in the context of power measurement, particularly in the realm of strength and conditioning research and practice.
Validity refers to the extent to which a test accurately measures the intended performance criterion, while reliability is the measure of the consistency or reproducibility of test results. In this context, before assessing validity, a measurement must first exhibit reliability. The text asserts that all measures of power discussed in the section are considered to have acceptable reliability.
However, when it comes to validity, the power measures are categorized into two groups: direct (more valid) and indirect (less valid) measures of system power. It emphasizes that not all methods for measuring power are equal in terms of their impact on validity and reliability. To ensure the reliability of power testing, several variables need to be controlled or kept constant, such as the testing equipment and calculation method, athlete instructions, time of day, athlete fatigue status, experience or training level, temperature, warm-up protocol, and the order of testing if multiple tests are performed. The more controlled the testing environment, the higher the reliability of the testing, which, in turn, allows for the detection of smaller changes in athlete performance.
The text mentions the concept of the “smallest worthwhile change,” which is determined statistically by multiplying 0.2 by the standard deviation for a given performance variable. This value represents the smallest meaningful change that must occur before it can be considered significant.
The discussion then focuses on direct and indirect power measurement, particularly in the context of ballistic activities. Direct measurement involves the use of tools like force plates and linear position transducers (LPT), which have become more accessible in recent times, enhancing the reporting of system power across various tasks. On the other hand, indirect measurement relies on predictive equations to estimate power output, but it is recommended to use jump height as a performance variable rather than relying on predictive equations due to their higher error rates.
The text advises against comparing power from different activities or combining direct and indirect measures, as this may lead to inaccurate conclusions. It provides a list of upper body, lower body, total-body, and rotational direct and indirect assessments of power for reference.
Direct measurement is considered the most valid for assessing system power and detecting minimal differences or worthwhile changes following training. The text then offers recommendations for practitioners on how to obtain valid and reliable system-power measurements. These include using direct measurements of velocity with LPTs and force plates, considering the use of two LPTs for movements with significant horizontal components, being cautious with accelerometers due to potential errors, and focusing on either force plates or bar velocity depending on the primary interest in power assessment. Sampling frequency is also addressed, emphasizing higher frequencies for specific measurements, and consistency in methodology is recommended for reliable results.
In summary, the text underscores the importance of validity and reliability in power measurement, outlines the differences between direct and indirect measurements, and provides recommendations for practitioners to ensure accurate and consistent assessments of system power during ballistic activities.
The provided text discusses two critical aspects of power measurement in the context of strength and conditioning: reporting power results and the presentation of testing data.
Firstly, the text mentions that power measurements can be expressed either in absolute terms (Watts, W) or normalized by factors like body mass (W·kg-1), known as ratio scaling. It introduces the concept of allometric scaling, which involves normalizing data to remove the influence of body size by dividing it by body mass raised to the two-thirds power (BM-0.67). The text points out that while allometric scaling can be beneficial, it also has its advantages and disadvantages. Notably, variations in body size, particularly in lean muscle mass across different athlete groups, can affect the effectiveness of this scaling method. As a solution, it suggests deriving an exponent specific to the characteristics of the group, such as gender, age, body mass index, and training history. However, using derived exponents may limit the ability to compare performance data across athletes with different body size characteristics. The text emphasizes that practitioners should understand the method of normalization used and its potential biases when interpreting power measurements.
Moving on to the presentation of testing data, the text discusses the importance of contextualizing power data within the test performed. While all movements, except isometric ones, produce power, comparing different exercises or loadings can be effectively evaluated using a standardized score, often termed a Z-score. A Z-score calculates how many standard deviations a value is above or below the mean and helps to understand how an athlete’s performance compares to the team. The text provides a formula for calculating the Z-score and showcases the difference between two versions of an athlete’s standardized data.
It presents a case where an athlete’s power production improved across different testing points, particularly during strength-focused and power-focused training blocks. This example illustrates how measured power data can be used to address specific questions about training effectiveness. The text stresses that practitioners should be aware of the different insights provided by various methods of data presentation. If the goal is to show the development of an athlete over time, it suggests presenting raw data or maintaining a constant mean and standard deviation. However, if the aim is to understand an athlete’s development compared to the team, a moving team mean and standard deviation at each testing point should be used. These two data presentation methods offer distinct perspectives on an athlete’s improvement, considering their progress relative to their own scores and the team’s average.
In summary, the text underlines the importance of understanding the nuances of reporting power results and the presentation of testing data. It acknowledges the complexities of allometric scaling and the need for careful consideration when using this approach, and it highlights the significance of choosing the appropriate data presentation method based on the specific goals of the analysis. This understanding is crucial for making informed decisions regarding training and athlete improvement.
The text explores the advantages and drawbacks of power assessment in the context of evaluating athletic performance. Power is commonly assessed in various ballistic movements and loading paradigms, often to determine the load that maximizes power. However, the text points out a potential drawback in this approach, which is the overemphasis on finding the load that maximizes power. Instead, it suggests a mixed-methods approach to effectively train the proposed power spectrum.
The text highlights that power, as a variable of mechanical construct, describes how the force-velocity profile shifts with different loads or activities but is less of a determinant of performance. To illustrate this, it presents an example of two athletes of similar body mass who produced similar power outputs during a vertical jump but had a 10% difference in performance (jump height). This example emphasizes that merely knowing the peak power (Ppeak) of these athletes would not provide additional insight into how they produce their power or the differences underlying their performance.
To understand the determinants of performance, the text suggests looking at impulse and, more specifically, time. It introduces the ratio of flight time to contraction time (FT:CT) as a metric for understanding the time aspect of performance. The example presented in the text shows that two athletes with similar jump height can have a 28% difference in FT:CT, while their jump height only differs by 10%. This discrepancy illustrates the importance of considering time, especially in sports where time limitations are critical.
The text emphasizes that power alone cannot provide a comprehensive understanding of athlete performance. While power is a valuable metric that combines force and velocity into a single measure, a deeper analysis is required to uncover the underlying determinants of athlete performance. The text suggests that power should not be used exclusively and advocates for the use of a force-velocity profile and the evaluation of different metrics beyond power to gain a more complete understanding of athlete performance.
In summary, the text highlights that while power assessment is essential in sports and performance analysis, it should not be the sole focus when evaluating athlete performance. A broader perspective that considers various variables, including time-related aspects, is necessary to understand the intricacies of performance.