Strength
Narrative Review
2019
A brief review: How much do we know about the 1RM testing protocol?
By Travis S.J. Baumgartner and Michael H. Stone
Journal of Strength and Conditioning Research, 33(4), pp. 1119-1126
<h2>Abstract</h2>
<p>The <a href="/terms/one-repetition-maximum/" class="term-link" data-slug="one-repetition-maximum" title="one-<a href="/terms/repetition-maximum/" class="term-link" data-slug="repetition-maximum" title="repetition maximum">repetition maximum</a>">one-repetition maximum</a> (1RM) test is the gold standard for measuring maximal dynamic strength in both research and applied settings. Despite its widespread use, substantial variability exists in how 1RM protocols are administered, raising concerns about the reliability and validity of results across laboratories and training facilities. This review by Baumgartner and Stone (2019) synthesizes current evidence on 1RM testing procedures, examining the influence of warm-up structure, inter-attempt rest intervals, and the number of attempts permitted on test outcomes. Available literature indicates that a progressive warm-up beginning at 50% of estimated 1RM and ascending through 80–90% is necessary to potentiate neuromuscular readiness without inducing fatigue. Rest intervals of 3–5 minutes between maximal attempts are consistently recommended to allow <a href="/terms/phosphocreatine/" class="term-link" data-slug="phosphocreatine" title="phosphocreatine">phosphocreatine</a> resynthesis and attenuate central fatigue [1, 2]. The number of attempts required to achieve a true 1RM typically ranges from 3 to 5, and exceeding this range has been associated with diminishing accuracy due to cumulative fatigue. Standardizing these variables improves intra- and inter-session reliability, making 1RM testing a more defensible measure of maximal strength for both practitioners and researchers.</p>
<h2>Introduction</h2>
<p>Maximal strength is one of the most fundamental physical qualities assessed in strength and conditioning practice, and the <a href="/terms/one-repetition-maximum/" class="term-link" data-slug="one-repetition-maximum" title="one-<a href="/terms/repetition-maximum/" class="term-link" data-slug="repetition-maximum" title="repetition maximum">repetition maximum</a>">one-repetition maximum</a> (1RM) has long served as the primary operational definition of this quality in applied and research contexts [1]. A 1RM is formally defined as the greatest external load an individual can successfully lift through the full <a href="/terms/range-of-motion/" class="term-link" data-slug="range-of-motion" title="range of motion">range of motion</a> of a given exercise for exactly one repetition, with failure occurring on any subsequent attempt at the same load [2]. This definition, while straightforward, belies the considerable complexity involved in administering the test in a manner that produces reliable and valid results.</p>
<p>The 1RM is used for multiple purposes: as a criterion measure for evaluating the effects of training interventions, as a baseline from which training loads are prescribed (typically as percentages of 1RM), and as a benchmark for tracking long-term progress in athletes and general populations alike [3]. Its use is documented across a remarkable range of populations, from elite powerlifters and Olympic weightlifters to elderly individuals in sarcopenia research and clinical rehabilitation settings. This breadth of application underscores the need for standardized testing procedures that can be reliably reproduced across different testers, sessions, and facilities.</p>
<p>Despite decades of use, the existing literature reveals a troubling lack of consensus regarding core procedural parameters. Reviews of published research consistently find substantial variation in the number and intensity of warm-up sets used prior to maximal attempts, the duration of rest intervals allowed between attempts, the total number of attempts permitted per session, and the criteria used to determine whether a lift is successful [4]. These inconsistencies make cross-study comparisons difficult and raise legitimate questions about whether reported 1RM values reflect the same construct across different testing environments.</p>
<p>Baumgartner and Stone (2019) undertook this review to consolidate existing evidence on 1RM protocol design and identify the procedural variables that most substantially influence test outcomes. The ultimate objective is to provide evidence-based recommendations that can serve as a practical guide for standardizing 1RM testing in both research and coaching contexts, thereby improving the interpretability and comparability of maximal strength data.</p>
<h2>Evidence Review</h2>
<h3>Warm-Up Structure</h3>
<p>The influence of warm-up on <a href="/terms/one-repetition-maximum/" class="term-link" data-slug="one-repetition-maximum" title="1RM">1RM</a> performance is well-documented, though the optimal warm-up structure remains a matter of some debate. A general progressive warm-up that elevates core temperature and prepares the neuromuscular system is universally accepted as necessary before maximal testing [1]. The specific loading scheme within the warm-up, however, varies considerably across studies and practice guidelines.</p>
<p>Current evidence supports a graduated approach to warm-up intensity. Spreuwenberg et al. demonstrated that warm-up sets at moderate intensities (50–80% of estimated 1RM) significantly enhance subsequent maximal performance compared to no warm-up or inadequate warm-up, primarily through enhanced <a href="/terms/motor-unit/" class="term-link" data-slug="motor-unit" title="motor unit">motor unit</a> recruitment and improved muscle tissue viscoelasticity [2]. A typical evidence-based warm-up sequence is as follows:</p>
<table>
<thead>
<tr>
<th>Set</th>
<th>Intensity (% of Estimated 1RM)</th>
<th>Repetitions</th>
<th>Rest Before Next Set</th>
</tr>
</thead>
<tbody>
<tr>
<td>1</td>
<td>50%</td>
<td>5–8</td>
<td>90 seconds</td>
</tr>
<tr>
<td>2</td>
<td>70%</td>
<td>3–5</td>
<td>2 minutes</td>
</tr>
<tr>
<td>3</td>
<td>80%</td>
<td>2–3</td>
<td>2–3 minutes</td>
</tr>
<tr>
<td>4</td>
<td>90%</td>
<td>1</td>
<td>3–4 minutes</td>
</tr>
<tr>
<td>First 1RM attempt</td>
<td>~95–100%</td>
<td>1</td>
<td>—</td>
</tr>
</tbody>
</table>
<p>Critically, too many warm-up sets or sets taken too close to failure can induce residual fatigue that attenuates maximal performance, a phenomenon directly relevant to why the number of warm-up sets should be minimized beyond the final preparation set [3].</p>
<h3>Rest Intervals Between Attempts</h3>
<p><a href="/terms/phosphocreatine/" class="term-link" data-slug="phosphocreatine" title="Phosphocreatine">Phosphocreatine</a> (PCr) resynthesis, the primary energy source for maximal-intensity efforts of 1–5 seconds, is approximately 70–80% complete within 2 minutes and nearly fully restored by 3–5 minutes after a maximal exertion [4]. This bioenergetic reality provides a physiological basis for <a href="/terms/inter-set-rest-interval/" class="term-link" data-slug="inter-set-rest-interval" title="rest interval">rest interval</a> recommendations. Studies that have directly manipulated inter-attempt rest in 1RM protocols consistently find that rest intervals shorter than 3 minutes result in significantly lower 1RM values compared to longer intervals, indicating that insufficient PCr resynthesis impairs the expression of true maximal strength [5].</p>
<p>Beyond metabolic recovery, central fatigue and residual voluntary activation deficits also resolve over similar time frames, further supporting minimum rest intervals of 3–5 minutes between maximal attempts.</p>
<h3>Number of Attempts</h3>
<p>The relationship between number of attempts and 1RM accuracy follows an inverted-U curve. Too few attempts and the lifter has not had sufficient opportunity to reach their true maximum; too many attempts and cumulative neuromuscular fatigue begins to depress performance [6]. The most commonly cited recommendation across practice guidelines and research protocols is to allow 3–5 maximal attempts per session. Allowing more than 5 maximal attempts substantially increases the probability that reported values reflect a fatigued state rather than genuine maximal capacity.</p>
<h3>Familiarization</h3>
<p>An often overlooked procedural variable is familiarization. Individuals unfamiliar with 1RM testing typically demonstrate 2.5–5% improvements in 1RM on repeated sessions in the absence of any training, reflecting learning effects related to technique and psychological readiness rather than true strength gains [7]. At least one full familiarization session prior to baseline testing is therefore strongly recommended, particularly in populations with limited resistance training experience.</p>
<h2>Discussion</h2>
<p>The findings consolidated in this review make a compelling case that the <a href="/terms/one-repetition-maximum/" class="term-link" data-slug="one-repetition-maximum" title="1RM">1RM</a>, while conceptually simple, is highly sensitive to procedural variables that are frequently underspecified in published research. The practical consequence of this sensitivity is that nominally identical tests administered under different conditions can yield meaningfully different results, compromising the internal validity of training studies and the external validity of normative data.</p>
<h3>The Warm-Up Problem</h3>
<p>One of the most practically significant insights from this review is that warm-up inadequacy is a more prevalent source of 1RM underestimation than excess fatigue from over-warming. Practitioners who allow athletes to approach their first maximal attempt without a sufficiently graduated warm-up are likely systematically underestimating true maximal strength. This has downstream consequences for load prescription: <a href="/terms/intermittent-fasting/" class="term-link" data-slug="intermittent-fasting" title="if">if</a> training loads are set as percentages of an underestimated 1RM, the resulting training stimulus will be below intended intensity thresholds [1].</p>
<p>Conversely, performing too many warm-up sets at high relative intensities can induce enough metabolic and neural fatigue to attenuate maximal performance. The optimal warm-up window is narrow, and the protocol outlined in the Evidence Review section represents a reasonable consensus from the available data.</p>
<h3><a href="/terms/inter-set-rest-interval/" class="term-link" data-slug="inter-set-rest-interval" title="Rest Interval">Rest Interval</a> Underestimation in Practice</h3>
<p>Anecdotal observation in competitive and recreational lifting environments suggests that rest intervals between 1RM attempts are frequently shorter than research recommendations. Coaches and athletes motivated by competitive zeal or time constraints often allow only 1–2 minutes between attempts. The <a href="/terms/phosphocreatine/" class="term-link" data-slug="phosphocreatine" title="phosphocreatine">phosphocreatine</a> kinetics literature makes clear that this practice imposes a meaningful energetic penalty on subsequent attempts [2]. Training facilities conducting 1RM testing should build adequate time into testing sessions and communicate clearly to athletes why full rest intervals are non-negotiable for accurate results.</p>
<h3>Ecological Validity of 1RM Testing</h3>
<p>A recurring concern in the literature is the degree to which laboratory 1RM conditions reflect the maximal strength expression possible in competitive settings. Athletes who regularly compete in powerlifting or weightlifting environments, where motivational arousal, audience presence, and performance-enhancing psychosocial factors are present, may express higher maximal forces than are captured in a quiet laboratory [3]. This discrepancy is difficult to fully eliminate but can be partially addressed through motivational standardization within testing sessions.</p>
<h3>Predictive Equations as Alternatives</h3>
<p>When direct 1RM testing is contraindicated by injury risk or population characteristics, several validated prediction equations (Brzycki, Epley, Lander) can estimate 1RM from submaximal repetition-to-failure tests [4]. These equations carry their own sources of error, particularly at very high repetition ranges, but represent a useful practical compromise in settings where maximal testing is inappropriate.</p>
<h2>Practical Recommendations</h2>
<p>The evidence reviewed by Baumgartner and Stone yields a set of actionable recommendations applicable to coaches, researchers, and athletes conducting <a href="/terms/one-repetition-maximum/" class="term-link" data-slug="one-repetition-maximum" title="1RM">1RM</a> assessments.</p>
<h3>Pre-Test Preparation</h3>
<ul>
<li><strong>Familiarization</strong>: Schedule at least one full practice session in the same exercise under similar conditions at least 48 hours before the criterion test. This minimizes learning-related variance in the actual test.</li>
<li><strong>Rest and Nutrition</strong>: Testing should occur following 24–48 hours of rest from intensive training, in a rested and adequately fueled state. Testing under conditions of accumulated fatigue will systematically underestimate true strength.</li>
<li><strong>Time of Day</strong>: Test at the same time of day across sessions where possible. Diurnal variation in strength performance is approximately 3–8%, with peak performance typically observed in the afternoon [1].</li>
</ul>
<h3>Warm-Up Protocol</h3>
<ol>
<li>Begin with a general cardiovascular warm-up (5–10 minutes at light-to-moderate intensity).</li>
<li>Perform 1–2 sets of the target exercise at 50% of estimated 1RM for 5–8 repetitions.</li>
<li>Perform 1 set at 70–75% for 3–5 repetitions.</li>
<li>Perform 1 set at 80–85% for 2–3 repetitions.</li>
<li>Perform 1 set at ~90% for 1 repetition.</li>
<li>Rest 3–4 minutes, then begin maximal attempts.</li>
</ol>
<h3>Maximal Attempt Strategy</h3>
<ul>
<li>Start the first attempt at 95–97% of the estimated 1RM based on prior training data or warm-up performance.</li>
<li>Increase load by 2–5% increments depending on the quality of each lift and the perceived exertion reported by the athlete.</li>
<li>Allow a minimum of 3 minutes and a maximum of 5 minutes between maximal attempts.</li>
<li>Limit total maximal attempts to 3–5 per session to avoid cumulative fatigue contaminating results.</li>
</ul>
<h3>Documentation and Standardization</h3>
<ul>
<li>Record all warm-up loads and repetitions, rest intervals, environmental conditions (temperature, time of day), and the athlete's subjective readiness rating.</li>
<li>Use consistent spotting and lift validation criteria across all sessions and assessors.</li>
<li>Apply the same protocol across all athletes within a research study or team testing battery to ensure internal comparability [2].</li>
</ul>
<p>By adhering to these standardized procedures, practitioners can substantially improve the accuracy and reproducibility of 1RM data, supporting more informed training load prescription and more meaningful research conclusions.</p>