Muscle Strength in ICU Patients Measured by Handgrip Dynamometer and ICU-Acquired Weakness: A Prospective, Single-Center Observational Study

Introduction

Intensive care unit-acquired weakness (ICU-AW) is an important neuromuscular complication in critically ill patients, severely limiting activities such as sitting, standing, and walking, often necessitating assistance with mobility [1]. Studies on ICU-AW demonstrate considerable heterogeneity. A systematic review by Stevens et al highlighted the variability in diagnostic criteria, making it challenging to draw consistent conclusions [2]. As a result, reported prevalence rates of ICU-AW vary widely, from 9% to 86% [3]. Several risk factors, including sepsis, hyperglycemia, prolonged immobilisation, extended mechanical ventilation, and the use of medications such as glucocorticosteroids, neuromuscular blocking agents, and vasoactive drugs contribute to the increased likelihood of developing ICU-AW [4].

ICU-AW can be classified into critical illness polyneuropathy (CIP), critical illness myopathy (CIM), critical illness neuromyopathy (CINM), and muscle deconditioning [5,6]. CIP is characterized by symmetric sensorimotor axonal polyneuropathy, affecting limb muscles, respiratory muscles, and sensory and autonomic nerves, potentially leading to greater weakness in the distal parts of the limbs and distal sensory disturbances. CIM results in weakness of the limb and respiratory muscles, with more pronounced proximal muscle weakness than distal, without sensory nerve involvement [5]. CINM, recognized as the most common cause of ICU-AW, is a condition in which CIP and CIM coexist [2,6,7].

A 2009 study by Schweickert et al demonstrated that early physical and occupational therapy in mechanically ventilated ICU patients was safe and well-tolerated. Additionally, it resulted in better functional outcomes at hospital discharge, reduced the duration of delirium, and increased the number of ventilator-free days compared to standard care [8].

Handgrip strength has been recognized as a reliable and clinically meaningful predictor of patient outcomes in the ICU. In a pivotal study, Ali et al demonstrated that reduced handgrip strength independently predicts poor functional recovery, regardless of diagnosis. Based on receiver operating characteristic (ROC) curve analysis, the authors proposed sex-specific cutoff values for the diagnosis of ICU-acquired paresis (a term preceding the now widely used ICU-AW): <11 kg for men and <7 kg for women. These thresholds offered the best balance between sensitivity and specificity when compared to the Medical Research Council (MRC) sum score [9]. The clinical utility and diagnostic performance of these thresholds have been subsequently supported by several independent studies. Among them, Parry et al provided external validation in a prospective cohort, confirming the high sensitivity (0.88) and specificity (0.80) of the proposed handgrip strength cutoffs [10]. Additional studies have further corroborated the diagnostic and prognostic value of handgrip dynamometry in diverse ICU populations [11–13]. Importantly, Parry et al introduced a two-tier diagnostic approach for ICU-AW, recommending the use of handgrip dynamometry as an initial screening tool. In patients with handgrip strength below the proposed sex-specific thresholds, manual muscle testing using an isometric technique was subsequently performed to confirm ICU-AW, defined as a MRC sum score below 24 on a modified 36-point scale [10].

Handgrip dynamometry predicts absolute muscle strength and provides insights into endurance. Its strong correlation with various clinical outcomes has made it a widely accepted measure of overall muscle strength. Due to its ease of use and accessibility, handgrip dynamometry is frequently employed as a standard method for assessing muscle strength in clinical settings, diagnosing weakness, and monitoring rehabilitation progress [14]. In 2014, Dodds et al conducted the first study that provided normative data on grip strength across the lifespan. Their findings showed that percentile values can inform clinical assessments of grip strength, which is considered an essential factor in identifying individuals with sarcopenia and weakness [15]. The 10th percentile of grip strength (P10) is often used as a cutoff point for sarcopenia, and reflects a clinically relevant threshold below which muscle strength is considered insufficient and associated with increased risk of impaired physical performance and functional decline. In contrast, the 50th percentile (P50) represents the median grip strength measured by dynamometry for a given sex and age, and may serve as a target value representing full functional recovery [16,17].

Given the gap in the literature regarding the progression of muscle strength during ICU stays, the primary objective of this study was to assess the time required to achieve muscle strength above the diagnostic threshold for ICU-AW (≥11 kg for men, ≥7 kg for women), as measured by the highest handgrip value, regardless of side. Additionally, the study aimed to identify factors associated with the duration of this process and to evaluate the time needed to achieve strength at the P10 and P50 levels.

Material and Methods

ETHICS STATEMENT:

All research procedures complied with the Declaration of Helsinki and the Medical University of Lublin Bioethics Committee guidelines. Medical University of Lublin Bioethics Committee approved the study, approval number KE-0254/46/02/2023. Written informed consent was obtained from each patient.

STUDY DESIGN AND PATIENT ELIGIBILITY:

A prospective, observational, single-center study was conducted between 2023 and 2024 at the ICU of the Medical University of Lublin in accordance with the ICU protocol and STROBE guidelines [18]. The ICU is a mixed unit with 21 beds, admitting patients with traumatic, surgical, and internal medicine conditions. This context provides a diverse patient population and enhances the generalizability of the findings.

Inclusion criteria required patients to have sufficient consciousness to understand and follow commands, no central nervous system injury, no fractures or injuries to the upper limbs, and to be over 18 years of age.

Exclusion criteria included unstable patient conditions, defined as a mean arterial pressure (MAP) below 65 mmHg or above 110 mmHg, systolic blood pressure above 200 mmHg, heart rate below 40 or above 130 beats per minute, respiratory rate below 5 or above 40 breaths per minute, or oxygen saturation below 88%. Additional exclusion criteria included elevated intracranial pressure, active blood loss, active myocardial ischemia, ongoing medical procedures (except for continuous renal replacement therapy), increased sedation, pregnancy, or refusal to participate in the study. Assessments were suspended exclusively on days when patients met the exclusion criteria.

EARLY REHABILITATION:

Patients whose clinical condition allowed underwent early rehabilitation, which included passive and active exercises in bed, passive and active sitting, standing up from the bed, and marching in place. The attending physician decided to enroll a patient in the early rehabilitation program based on the patient’s overall condition. For patients unable to sit independently, rehabilitation involved support in a seated position by a physiotherapist (passive sitting). Patients with sufficient muscle strength began with active exercises in bed, followed by independent sitting with their legs lowered over the edge of the bed and feet resting on the floor (active sitting). If the patient tolerated the sitting position well, attempts were made to achieve full standing with the assistance of a standing aid (Sara Stedy, Arjo, Inc.). If successful, the patient performed marching in place by alternately lifting their legs to simulate walking. Rehabilitation sessions were conducted 5 days a week on weekdays. This frequency aligns with current evidence suggesting that early rehabilitation delivered ≥5 days per week significantly improves functional outcomes in ICU patients [19]. Passive exercises in bed lasted 30 minutes per session, while standing and marching in place were performed for 15 minutes, unless the patient’s condition required an earlier termination of the session. Rehabilitation was conducted by 2 physiotherapists who were experienced in ICU patient rehabilitation. Throughout the study period, the same 2 physiotherapists provided the rehabilitation.

HANDGRIP STRENGTH MEASUREMENT:

Handgrip strength was measured using a hydraulic dynamometer (SH5001 model, Saehan, Korea) following standard testing protocols. Participants were instructed to sit with their forearm flexed at a 90-degree angle, keeping the arm in a neutral position without touching the torso (Figure 1). The patient held the device unassisted, and the grip size of the dynamometer was adjusted to fit the patient’s hand. Before starting the measurement, patients were instructed on the procedures and protocol. Upon the command “start,” participants squeezed the dynamometer with maximum strength until the command “stop” was given. The measurement was repeated 3 times for each hand, with results recorded based on the maximum needle reading, reset to zero before each subsequent measurement. Participants were given short rest periods between measurements. The dynamometer was disinfected before each use to ensure safety and hygiene [16]. The highest value, regardless of side, was used in the analysis. The primary outcome was the day of hospitalization when the patient achieved a handgrip strength above the diagnostic threshold for ICU-AW (≥11 kg for men, ≥7 kg for women). [9]. Secondary outcomes included factors affecting the time needed to reach this strength and the days the patient achieved strength at the P10 and P50. The P10 and P50 strength values were derived from Dodds et al [15]. Measurements were performed until the end of their ICU stay.

Grip strength was expressed in kilograms (kg), in line with the standard reporting practice used in most clinical studies on ICU-AW, including those by Ali et al [9]. Normative reference values for the general population, such as those published by Dodds et al [15], are likewise reported in kilograms, supporting consistency across clinical and epidemiological research. Furthermore, widely accepted guidelines, including those from the European Working Group on Sarcopenia in Older People (EWGSOP2), define reduced handgrip strength using kilogram-based thresholds (<27 kg for men and <16 kg for women), derived directly from the normative data reported by Dodds et al [15,20]. The use of kilograms is also consistent with the scale of the Saehan SH5001 dynamometer used in this study, which features dual-unit markings in kilograms and pounds.

CLINICAL DATA COLLECTION:

Clinical data related to the course of hospitalization, including the duration of mechanical ventilation, pharmacological sedation, ICU stay, catecholamine administration, and time to regain consciousness, were collected retrospectively from patients’ medical records after completion of hospitalization. The data were independently extracted by 2 researchers and subsequently compared to ensure consistency and avoid errors.

STATISTICAL ANALYSIS:

Categorical variables were described using absolute counts and percentage shares. Continuous variables were assessed for normal distribution using Shapiro-Wilk test, which tests whether the data are normally distributed and variance homogeneity using Levene’s test, which checks whether variances are equal across groups. Data were presented as means±standard error (SE). When the assumption of normal distribution was not met, data were presented as medians with interquartile ranges (IQR). The predefined thresholds for handgrip strength were sex-specific, based on reference values – ≥7 kg for women and ≥11 kg for men – which is why the mean and median values are presented separately for both sexes to adjust for sex-related differences in the parameters potentially influencing achieving this level.

The Kaplan-Meier method, a non-parametric estimator of time-to-event probabilities, was used to estimate the probabilities of reaching predefined handgrip strength thresholds (grip strength ≥7 kg for women and ≥11 kg for men) and achieving P10 and P50 levels. Two definitions of follow-up time were used: (I) from ICU admission and (II) the start of strength measurements until the event. The estimated probabilities were presented by Kaplan-Meier survival curves, which have a characteristic stepped appearance because the estimated probability changes only at time points when events occur. This type of plot is standard for visualizing time-to-event data, such as recovery of strength. Median times, event probabilities, and quartile estimates were calculated, with right-censoring for subjects who did not reach the event [21]. Mortality was monitored during the follow-up period. Among the 178 patients, only 3 deaths were observed, all of which reached the predefined grip strength thresholds prior to death. Therefore, these cases were censored after the event occurred. Given the very low mortality rate and the fact that death did not preclude the occurrence of the event of interest, a competing risk analysis was not applicable and was not performed [22].

A multivariable Cox proportional hazards (PH) model was applied to assess prognostic factors and their combined impact on regaining strength. Variables for the multivariable Cox PH model were selected a priori based on clinical knowledge and previous research. The selected variables included sex, age (years), height (cm), weight (kg), duration of ICU stay (days), duration of pharmacological sedation (days), duration of mechanical ventilation (days), duration of catecholamine administration (days), time to regain consciousness (days), and strength at first measurement (kg). These variables were chosen due to their known influence on muscle strength recovery and clinical relevance in critically ill patients. Clinically justified interactions and time effects were also explored. To assess the multicollinearity of variables, VIF (Variance Inflation Factor) coefficients were calculated. The variables or their interactions with VIF higher than 5 were removed from the further analysis. The Cox PH assumption was tested using scaled Schoenfeld residuals. Influential observations were checked using dfBETA, which threshold was set at =0.15, where n is the number of observations [23].

All the statistical evaluations were performed using a two-sided approach, with a significance threshold of α=0.05. The statistical assessments were conducted using RStudio (2023.09.1, build 494, Integrated Development for R. RStudio, PBC, Boston, MA URL http://www.rstudio.com/), STATISTICA 13.0 (TIBCO Software, Palo Alto, CA, USA), and OriginPro 2022 (OriginLab, MA, USA) software. The post hoc power analysis was computed using PASS 2024, version 24.0.4, using a one-sample log rank test and Schoenfeld method for Cox PH regression (two-sided significance level of α=0.05).

Results

GENERAL CHARACTERISTICS:

The study was conducted between 2023 and 2024 at the ICU of the Medical University of Lublin. During this period, 337 patients were hospitalized, of whom 134 were excluded due to a lack of regained consciousness by the end of their ICU stay and 25 due to upper limb conditions or injuries. Consequently, 178 patients were ultimately enrolled in the study.

Among the 178 patients included in the study, the most common primary reasons for ICU admission were internal medical conditions (n=56, 31.46%), trauma (n=52, 29.21%), and surgical indications (n=50, 28.09%). Additionally, 20 patients (11.24%) were admitted due to acute neurological events. It is important to note that in many cases, patients presented with overlapping conditions, which made precise classification challenging.

The studies were done on n=57 women (32.02%) and n=121 men (67.98%). The mean age of the patients was 55.98±1.42 years, with women being older on average than men (63.93±2.37 years vs 52.17±1.65 years, respectively). Patients stayed in the ICU for a median of 16.00 days. The duration of ICU stay, sedation, mechanical ventilation, catecholamine administration, and time to regain consciousness did not differ between sexes. However, statistical analysis revealed that women had nearly 8 kg less strength on the first-day strength measurements than men, which was statistically significant at P<0.001. The detailed characteristics of patients by gender are presented in Table 1.

STRENGTH ABOVE THE ICU-AW CUTOFF:

The study’s primary outcome was the time until patients achieved handgrip strength at or above the sex-specific ICU-AW cutoff (≥7.0 kg in women, ≥11.0 kg in men), while ICU-AW itself was defined as <7.0 kg in women and <11.0 kg in men. The analysis was performed for the entire group of patients, as there were no significant differences between sexes in the average time needed to achieve the expected value of handgrip strength, measured from ICU admission (I) and the first handgrip strength measurement (II). Post hoc power analysis for the Kaplan-Meier time-to-event estimation, conducted using a one-sample log rank test, proved that for both observation times the power exceeds 0.90, confirming that the presented time-to-event analyses had sufficient power to detect clinically meaningful deviations from the survival thresholds (10 and 2 days, respectively), based on the literature [24,25].

TIME MEASURED FROM ICU ADMISSION (I):

Kaplan-Meier analysis showed that among the studied 178 patients, 89% should reach the required strength level over the observation time. When measured from ICU admission, the estimated mean time to reach the cutoff strength was 26.84±2.30 days. After 70 days, there was no increase in patients’ regaining strength when the observation time from ICU admission was considered (Figure 2). The probability remained constant at 0.89. Quartile analysis of the probability of achieving muscle strength above the ICU-AW cutoff, defined as below 7.0 kg for women and 11.0 kg for men, showed that from the moment of ICU admission, 25% of patients were estimated to achieve the cutoff strength within 5 days, 50% within 13 days, and 75% within 41 days (Figure 2, Table 2).

TIME MEASURED FROM THE FIRST STRENGTH MEASUREMENT (II):

Analysis conducted over follow-up from the first measurement of the strength to the end of the observation or patient removal from the study showed that the estimated mean time to reach the cutoff strength was 21.32±2.62 days. Two characteristic points are visible in the graph showing the probability of achieving strength above the ICU-AW cutoff: the first after 23 days, when probability stabilized at 77% until the 49th day, when it increased to 0.80 and remained constant until the end of the observation period (Figure 3). When measured from the first strength assessment, 25% of patients were estimated to achieve the cutoff after 1 day. The median was also 1 day (with a confidence interval of 1 to 4 days), and 75% of patients were estimated to achieve the cutoff strength after 33 days (Figure 3, Table 2).

VARIABLES ASSOCIATED WITH THE TIME TO ACHIEVE STRENGTH ABOVE THE ICU-AW CUTOFF:

Cox regression analysis was used to estimate hazard ratios (HR) and explain the dependent variable – achieving handgrip strength above the ICU-AW cutoff. Possible predictor variables included sex (with females as a reference level), age, weight and height at the start of the study, and time-dependent variables such as duration of ICU stay, sedation duration, duration of mechanical ventilation, catecholamine administration, day of regaining consciousness, and strength value obtained in the first measurement. The analysis was conducted for the follow-up, starting with the first strength measurement. It was conducted in multivariate mode, including main variables and clinically important interactions. Variables and interactions that did not demonstrate a significant impact or show a VIF higher than 5 were removed from the model (Table 3, variables assigned with #; Duration of ICU stay: Sex and Weight: Sex interactions). Ultimately, the analysis showed (Table 3) that among the chosen variables, only weight, sedation, ICU stay, time to regain consciousness, strength at first measurement, and duration of mechanical ventilation were statistically significant (Table 3).

The P value for the duration of sedation and duration of ICU stay and mechanical ventilation was lower than 0.001, with HR below 1 (0.805, 0.746, and 0.860, respectively), indicating a strong relationship between these variables and the likelihood of achieving handgrip strength above the ICU-AW cutoff. HR values show that with each additional day of sedation, ICU stay, or mechanical ventilation decreases the probability of achieving handgrip strength ≥11 kg (men) or ≥7 kg (women) by approximately 19.5% with sedation, 25.4% with ICU stay and 14.0% with mechanical ventilation. Similarly, each day of being unconscious decreased the probability of achieving the assumed level of strength by about 6% (HR=0.942, p=0.016). Described effects remained consistent throughout the study, assuming the PH assumption holds. The weight of patients, strength measured during the first handgrip assessment and duration of mechanical ventilation and sex interaction were also significantly associated with the likelihood of achieving strength above the ICU-AW cutoff, with HR being higher than 1 (1.041, 1.045, and 1.138). Higher patient weight was significantly associated with a shorter time-to-event (each kilogram increased the probability by about 4%). In comparison, each 1-unit increase in strength at the first measurement was associated with a 4.5% higher likelihood of reaching the target strength. Interestingly, the interaction of mechanical ventilation and sex showed that mechanical ventilation increases “the risk” of reaching an event sooner in men by about 13.8%.

Assessing the model, the P value for the overall test (Wald test=60.94), less than 0.001, indicates that the model is highly significant and that the included variables collectively contribute meaningfully to predicting the outcome. Additionally, the model’s predictive accuracy evaluated using the C-index, which was calculated to be 0.967 (±0.014), suggests that, in almost 97% of the pairs of subjects for whom a comparison can be made, the model correctly identifies the subject with the higher predicted risk as the one who experiences the event (physical recovery) sooner. This high C-index reflects the model’s discriminatory solid power in accurately predicting which patients are more likely to recover faster based on the variables included in the model. Post hoc power analysis calculation, based on ICU stay duration in the Cox PH model (HR=0.746), showed that with 178 observed cases, assuming R²=0.20, the achieved power was estimated at 0.909 (two-sided α=0.05), confirming sufficient power of the model to detect clinically relevant effects.

The model built was then assessed using the PH assumption across applied covariates (Schoenfeld test). The results (Table 4) showed that the assumption of PH appears to be supported, and there is no pattern with time, as the relationship between the residuals and time proved not to be significant (P>0.05).

Additionally, comparing the magnitudes of the most significant dfBETA values to the regression coefficients suggests that no single observation significantly influences the model, as presented in Figure 4, where residual plots for each covariate in the Cox PH model are shown. These plots illustrate the influence of individual observations on the estimated regression coefficients.

It can then be assumed that all necessary assumptions for the Cox PH model were thoroughly tested and met. The mentioned evaluations confirm that the Cox regression model fits the data and provides reliable and robust estimates of the hazard functions associated with the studied covariates.

STRENGTH AT THE P10 AND P50 LEVELS:

P10 and P50 levels were determined considering age and sex. The probability of reaching the expected level of strength was calculated using Kaplan-Meier analysis. Probability curves for achieving strength at the P10 and P50 (Figure 5) levels during the ICU stay indicate that over the entire observation period, approximately 32% of patients were estimated to reach P10, while almost 9% were estimated to reach P50. Flat segments were observed from the 19th day for P10 (except for the 46th day, when 1 patient achieved strength at the P10 level) and from the ninth day to the end of the ICU stay for P50. This indicates that, during these time intervals, none of the patients achieved the specified strength levels except for 1 case on the 46th day. Quartile estimates further revealed that 25% of patients were estimated to achieve P10 strength after approximately 11 days. Estimates for the remaining quartiles were unavailable due to the small number of patients reaching the P10 strength level. It should be underlined that most observations, when estimating probabilities of reaching P10 and P50 levels, were censored, and some of the estimates provided by the analysis may lack precision. However, the results are still helpful in identifying trends and generating hypotheses for future studies.

Discussion

This study provides valuable insights into the probability of ICU patients achieving muscle strength above the ICU-AW cutoff, defined as below 7.0 kg for women and 11.0 kg for men. The loss of muscle strength was comparable between men and women, confirming the findings of previous studies [26]. Quartile analysis of the probability of reaching the strength threshold showed that from the moment of ICU admission, 25% of patients were estimated to have a probability of achieving the cutoff within 5 days, 50% within 13 days, and 75% within 41 days. These results highlight that while the estimated mean time for the entire patient group to reach the cutoff strength was 26.84±2.30 days from ICU admission, the probability distribution indicates significant individual variability. Additionally, the analysis of the probability of achieving muscle strength above the previously mentioned cutoff from the initiation of strength measurements showed that 25% of patients were estimated to reach this level after just 1 day. The median probability was also 1 day (with a confidence interval of 1 to 4 days), and 75% of patients were estimated to achieve strength above the cutoff after 33 days from the start of measurements.

These results highlight the varying rehabilitation needs of ICU patients and the potential importance of tailoring interventions to the individual needs of each patient to support their recovery process. It is important to note that the strength considered as the cutoff in this study represents a diagnostic threshold for ICU-AW, not full physical strength [9]. For comparison, our study found that the probability of achieving strength at the P10 level, often used as a criterion for diagnosing sarcopenia, during the ICU stay was 32%. In comparison, the probability of reaching P50 was just under 9% [15,16]. Additionally, the multivariate Cox regression analysis conducted in this study suggested that a longer duration of mechanical ventilation may prolong the time required to regain muscle strength above the ICU-AW cutoff, while greater strength measured on the first day using a dynamometer may shorten the time needed to achieve the expected muscle strength. These findings align with those of previous studies [1,11,13,27–29].

The substantial individual variability in time to regain adequate muscle strength highlights the importance of implementing personalised rehabilitation strategies in the ICU setting. Rather than applying uniform rehabilitation protocols, it may be beneficial to incorporate routine handgrip strength measurements as an early prognostic indicator. The strength measured using a dynamometer could support the selection of an appropriate rehabilitation program, helping to adjust the intensity, frequency, and progression of therapeutic interventions to the patient’s functional capacity. This approach could optimize recovery and improve the efficiency of care in critically ill patients.

The observed association between greater strength on the first day of measurement and the speed of achieving the expected muscle strength may indicate a potential role for early physiotherapeutic intervention in improving treatment outcomes. However, it is important to acknowledge that this study did not collect data on specific physiotherapy interventions or include physiotherapy as a confounder in the analysis. Thus, the relationship between initial strength and recovery speed should be interpreted cautiously, and no definitive conclusions regarding the effectiveness of physiotherapy can be drawn. Additionally, since many ICU patients are undergoing elective surgical procedures, these findings may highlight the potential importance of prehabilitation in reducing the risk of ICU-AW. Sarcopenia, a progressive and generalized process of muscle atrophy, is most commonly associated with aging but can also occur in younger individuals due to nutritional deficiencies, physical inactivity, or illness. Studies indicate that the global prevalence of sarcopenia ranges from 10% to 27% in individuals aged 60 and older [30]. With advances in medicine and increasing life expectancy, sarcopenia is becoming an important, modifiable risk factor for adverse outcomes in individuals preparing for surgery [31]. Therefore, prehabilitation involving respiratory muscle strengthening exercises, aerobic training, and resistance exercises [32], and appropriate nutritional management [33] in other hospital units may positively influence treatment and rehabilitation outcomes for ICU patients following surgical procedures, potentially reducing the risk of complications associated with ICU-AW. However, this study did not directly assess the effectiveness of prehabilitation, and its role requires further investigation.

Moreover, studies have shown that a rehabilitation strategy involving early sedation interruption and the initiation of physiotherapy within the first days of critical illness appears to be safe, well-tolerated, and can contribute to better functional outcomes at hospital discharge, a reduction in delirium duration, and an increase in ventilator-free days compared to standard care [8,34]. This study demonstrated that prolonged sedation significantly reduces the likelihood of achieving strength above the ICU-AW cutoff. These findings highlight the importance of early and optimized sedation management as a component of rehabilitation strategies to support faster muscle strength recovery and improve overall patient outcomes.

The results show the importance of optimizing sedation management and early rehabilitation to maximise functional outcomes in ICU patients and the potential role of prehabilitation in patients admitted to the ICU following surgical procedures. They also emphasize the significance of precise monitoring of muscle strength as an indicator of recovery progress and as a tool for appropriately adjusting exercises to the patient’s individual capabilities, thereby optimizing the rehabilitation process. Future research should focus on identifying optimal strategies that could shorten the time needed to regain muscle strength, thus minimizing ICU stay, post-discharge rehabilitation time, and associated costs. Additionally, future studies should investigate what muscle level of strength, measured by a dynamometer, allows for the proper adjustment of rehabilitation programs to the patient’s condition, which may further improve therapy outcomes.

Despite the significant conclusions drawn from this study, several limitations should be considered when interpreting the results. While weight, initial muscle strength, duration of sedation, duration of ICU stay, time to regain consciousness, and duration of mechanical ventilation were identified as significant predictors of recovery, other potentially influential factors, such as pre-hospitalization physical activity levels, nutritional status, muscle mass, and comorbidities, were not included in the analysis. The lack of control over these variables might have influenced the results and their interpretation. Future research should incorporate these factors to provide a more comprehensive understanding of their impact on muscle recovery rates and to refine rehabilitation strategies further.

Conclusions

This study highlights the variability in muscle strength recovery among ICU patients and emphasizes the need for individualized rehabilitation strategies. Identifying factors such as pharmacological sedation, ICU stay, and initial muscle strength allows for tailoring interventions to patient-specific needs. Optimizing these factors could improve recovery rates and overall outcomes. Future research should focus on refining rehabilitation programs and exploring strength thresholds for guiding physiotherapeutic interventions.