European Journal of Cardiovascular Medicine

Nerve conduction velocity (NCV) is a key neurophysiological parameter used in clinical and research assessments of peripheral nerve function. It reflects how quickly an electrical impulse travels along a peripheral nerve and is influenced by factors such as axon diameter, degree of myelination, limb temperature, and other physiological properties¹. NCV is valuable in diagnosing various neuropathies and demyelinating disorders, where conduction speed is reduced².

Anthropometric factors—including age, gender, height, weight, body mass index (BMI), and limb length—have been shown to influence NCV measurements across populations³. Age and height are consistently reported to be negatively correlated with conduction velocity: conduction slows by approximately 1 m/s for every decade of life beyond adulthood, and taller individuals exhibit slower NCV due to longer nerve path lengths⁴. Gender differences have also been observed, with females often showing faster NCV and higher sensory amplitudes, potentially due to smaller limb dimensions and less subcutaneous tissue⁵.

Limb length—or more specifically the distance between stimulation and recording sites—has been hypothesized to affect NCV. While some early studies suggested that increased limb length would lead to reduced conduction velocity, more controlled analyses have concluded that no consistent correlation exists between upper-limb length and NCV when temperature is standardized⁶. However, other investigations—particularly multivariate work accounting for arm, forearm or wrist dimensions—report that anthropometric distances may influence latency, amplitude, and velocity in both median and ulnar nerves⁷.

Several cross-sectional studies conducted in the Indian subcontinent have explored these associations. In a North Indian cohort (n = 87), Singh et al. found significant correlations between BMI and motor latency, and between waist–hip ratio and motor NCV; height and weight were also implicated as modulators of nerve conduction parameters⁸. Pawar et al. showed minimal associations between BMI and NCV, though they reported prolonged distal motor latency in median nerves with higher BMI⁹. Other large Indian studies among elderly subjects (n ≈ 382) confirmed that age, height and BMI independently predicted slower conduction velocity, increased latency, and reduced amplitudes in both motor and sensory studies¹⁰.

There is limited data, however, specifically examining the role of limb lengths—for instance, upper arm or forearm length—independent of overall height, particularly in Eastern India or urban West Bengal. A recent West Bengal–based study (AIIMS Kalyani, 2023) assessed normative median nerve parameters using fixed-distance recording and reported that measures including arm length, forearm length, wrist circumference and BMI significantly affected latency and amplitude in gender-specific regression models¹¹. That study emphasizes the need for region-specific anthropometric norms to enhance diagnostic precision for peripheral nerve conduction.

Thus, despite broader literature supporting anthropometric influences on NCV, the specific correlation between limb length (arm/forearm) and NCV remains under-explored in urban populations of West Bengal. Given regional variations in body habitus and anthropometry, especially across Indian states, localized normative data and correlation analyses are warranted¹².

Moreover, most existing work has focused on upper-limb nerves such as median and ulnar. Studies on lower-limb nerves (e.g., peroneal, tibial, sural) show similar patterns of age-related slowing and decreased amplitude but seldom consider limb lengths in analysis¹³.

Understanding the relationship between limb length and NCV has both theoretical and practical relevance. From a physiological standpoint, longer limbs may prolong nerve path length and increase latency while lowering velocity. Clinically, adjusting for limb length might refine interpretation of NCS, reducing false-positive (over-diagnosis in taller individuals) or false-negative (under-diagnosis in shorter individuals) results¹⁴.

Therefore, this study aims to conduct a cross-sectional evaluation among healthy participants residing in urban areas of West Bengal, measuring upper- and lower-limb lengths (e.g., arm length, forearm length, leg length) and performing nerve conduction studies on selected peripheral nerves. Our objectives are to:

1. To measure nerve conduction velocity (NCV) of selected motor and sensory nerves in healthy adults.
2. To measure upper and lower limb lengths of the study participants.
3. To assess the correlation between limb lengths and NCV.
4. To determine the influence of demographic and anthropometric factors (age, sex, height, BMI) on NCV.

This investigation seeks to fill a gap in regional neurophysiological databases, offering clinicians and researchers in West Bengal improved reference standards and insights into how limb length influences nerve conduction in the local urban adult population.

This cross-sectional observational study was conducted in the Department of Physiology, Burdwan Medical College and Hospital, West Bengal, over a period of one year. The study population comprised healthy adult volunteers aged 18 to 60 years, residing in urban areas of West Bengal, who provided written informed consent prior to participation. Participants were recruited through voluntary screening at outpatient services and general health awareness camps.

Exclusion criteria included a history of neuromuscular diseases, diabetes mellitus, thyroid disorders, chronic systemic illnesses, prior trauma or surgery involving the limbs, or current use of medications known to affect nerve conduction. Pregnant women were also excluded. All participants underwent a thorough clinical examination to confirm eligibility.

Anthropometric measurements recorded included age, sex, height, weight, and body mass index (BMI). Limb lengths were measured using a standard, non-stretchable measuring tape. Upper limb length was measured from the acromion process to the tip of the middle finger with the arm fully extended, while forearm length was measured from the lateral epicondyle of the humerus to the styloid process of the radius. Lower limb length was measured from the anterior superior iliac spine to the medial malleolus. All measurements were performed in the anatomical position by the same observer to avoid inter-observer variability.

Nerve conduction studies were performed in a temperature-controlled neurophysiology laboratory maintained at 22–25°C, using the NIHON KOHDEN Neuropack EMG/NCV/EP system. Sensory nerve conduction parameters were assessed bilaterally in selected nerves, including the median and tibial nerves, following standardized procedures for supramaximal percutaneous stimulation and surface electrode recording. To minimize the effect of limb dominance, bilateral recordings were performed, and the mean value was used for analysis. Skin temperature near the recording site was maintained above 32°C. All procedures were conducted by the same trained technician to ensure procedural consistency.

Data were compiled using Microsoft Excel and analyzed with Jamovi version 2.5.6. Continuous variables are expressed as mean ± standard deviation, and categorical variables as percentages. The relationship between nerve conduction velocity (NCV) and limb lengths was assessed using Pearson’s correlation coefficient. Multiple linear regression models were employed to adjust for potential confounding factors, including age, sex, height, and BMI. A two-sided p-value of less than 0.05 was considered statistically significant.

Table 1: Demographic and Anthropometric Characteristics

The study included a total of 60 healthy adults, with equal distribution among sexes (30 males and 30 females). The mean age of participants was 33.3 ± 11.7 years in males and 35.7 ± 11.9 years in females, with no statistically significant difference (p = 0.41). However, males had significantly greater height (164.1 ± 8.6 cm vs. 155.6 ± 8.5 cm, p < 0.001) and weight (73.3 ± 11.9 kg vs. 61.5 ± 11.2 kg, p < 0.001) compared to females. While BMI showed a higher trend in males (27.3 ± 3.3) than females (25.4 ± 4.2), the difference was not statistically significant (p = 0.06). As expected, males had significantly longer upper limb lengths (74.1 ± 4.1 cm vs. 67.5 ± 4.5 cm, p < 0.001), while lower limb lengths did not differ significantly between sexes (p = 0.17) (Table 1).

Table 2: Nerve Conduction Velocity (NCV) by Sex

When comparing NCV values, males had significantly faster nerve conduction than females across all measured nerves and sides. For the median nerve, the NCV was higher in males on both the right (55.3 ± 3.2 m/s vs. 52.9 ± 2.3 m/s; p = 0.001) and left (56.3 ± 3.0 m/s vs. 53.2 ± 2.1 m/s; p < 0.001) sides. Similarly, for the tibial nerve, males exhibited higher NCV on both the right (46.4 ± 3.0 m/s vs. 43.1 ± 2.7 m/s; p < 0.001) and left (46.4 ± 3.3 m/s vs. 42.7 ± 2.5 m/s; p < 0.001) sides (Table 2).

Table 3: Correlation Between Limb Lengths and NCV (Pearson’s r)

A significant negative correlation was observed between upper limb length and median NCV, more pronounced in females. In males, upper limb length negatively correlated with right median NCV (r = –0.35, p = 0.002), while the correlation with left median NCV was weaker and statistically non-significant (r = –0.31, p = 0.191). Among females, stronger correlations were noted on both sides: right median NCV (r = –0.42, p = 0.007) and left median NCV (r = –0.40, p = 0.037).

For the tibial nerve, only females demonstrated significant negative correlations between lower limb length and NCV. The correlation between lower limb length and right tibial NCV was r = –0.32 (p = 0.014) among females, while the same in males was weaker and non-significant (r = –0.25, p = 0.073). No significant correlations were noted between lower limb length and left tibial NCV in either sex (Table 3).

Table 4: Multiple Regression Analysis (NCV vs. Limb Lengths + Age/BMI)

In order to identify independent predictors of NCV, multiple regression models were constructed. In males, upper limb length was a significant predictor of right median NCV (β = 0.38, p = 0.02), while age had a weaker, non-significant inverse effect (β = –0.21, p = 0.11). In females, both upper limb length (β = 0.44, p = 0.01) and age (β = –0.29, p = 0.03) independently predicted right median NCV. Regarding tibial NCV, lower limb length was a borderline predictor in males for left tibial NCV (β = 0.31, p = 0.07), whereas it was statistically significant in females (β = 0.36, p = 0.04). BMI did not significantly predict NCV in either group (Table 4).

Figure 1: Scatter plot showing Upper Limb Length vs Median Sensory NCV

Figure 1 depicts the scatter plot between upper limb length and median sensory NCV, demonstrating a clear negative linear relationship. As upper limb length increases, the conduction velocity in the median sensory nerve tends to decrease. This inverse trend was more marked in female participants, consistent with the Pearson’s correlation analysis showing significant negative correlation values.

Figure 2: Scatter plot showing Lower Limb Length vs Tibial Sensory NCV

Figure 2 illustrates the scatter plot of lower limb length versus tibial sensory NCV, also showing a mild negative correlation. Though the dispersion was more variable compared to upper limbs, the downward trend indicates that longer lower limbs are associated with slower tibial sensory conduction, particularly among female subjects, supporting the statistical results of the correlation matrix.

• These graphical representations reinforce the core finding of the study: limb length inversely correlates with sensory nerve conduction velocities, which may have physiological and clinical implications in the normative interpretation of NCV studies.

In our study of 60 healthy adults from Burdwan Medical College and Hospital, we found that males had significantly higher nerve conduction velocities (NCV) across all nerves studied. This was accompanied by significantly greater height, weight, and upper limb length in males as compared to females. Notably, while the body mass index (BMI) did not differ significantly between sexes, males showed faster NCV in both the median and tibial nerves. For instance, the right median NCV was 55.3 ± 3.2 m/s in males versus 52.9 ± 2.3 m/s in females (p = 0.001), while the left was 56.3 ± 3.0 m/s in males versus 53.2 ± 2.1 m/s in females (p < 0.001). This trend was also observed for tibial nerves. Although some studies such as Shelly et al.¹⁵ reported that females typically have faster NCV due to shorter conduction distances and less subcutaneous tissue, our findings contradict this, likely due to longer limb lengths in males that may introduce greater nerve conduction path and possibly better myelination and axonal integrity. Similar regional variations were also noted in the study by Palve et al.¹⁶, who found that demographic differences could significantly alter the typical sex-based trends seen in western populations. Hence, our study adds to the growing body of evidence suggesting that normative NCV values need to be tailored for specific populations.

A central observation in our analysis was the negative correlation between limb length and NCV. This inverse relationship was particularly prominent in females for both upper and lower limbs. In the case of median nerve NCV, females showed stronger and statistically significant negative correlations on both sides (right: r = –0.42, p = 0.007; left: r = –0.40, p = 0.037), while in males, the correlation was significant only on the right (r = –0.35, p = 0.002). These findings align with the observations of Hennessey et al.¹⁷, who demonstrated a strong negative correlation between arm length and NCV of the median nerve in their study population. Interestingly, in contrast, Shelly et al.¹⁵ suggested that limb length may not have a significant impact on NCV when other anthropometric factors such as BMI and height are considered. Our results challenge that notion, particularly since limb length remained an independent predictor of NCV even after adjusting for age, sex, height, and BMI in our regression analysis. This suggests that while general height may loosely correlate with NCV, specific segmental limb measurements like arm and forearm length have a more direct influence on conduction velocity due to their closer association with the actual conduction path of peripheral nerves.

The relationship between lower limb length and tibial NCV was less consistent but still revealed notable sex-based differences. In females, there was a statistically significant negative correlation between lower limb length and right tibial NCV (r = –0.32, p = 0.014), whereas in males the correlation was weak and statistically non-significant (r = –0.25, p = 0.073). This is in concordance with the findings of Song et al.¹⁹, who reported that leg length and height inversely influenced tibial nerve conduction velocities, especially in females. Our data also aligns with the broader conclusions of Soudmand et al.¹⁸, who demonstrated that increased stature—and by extension limb length—negatively affected peroneal and sural NCVs. However, they found no such effect on median nerves, possibly due to the shorter conduction path in upper limbs or compensatory mechanisms that offset distance-related delay. In contrast, we observed an effect even in upper limbs, especially among females, which may indicate population-specific variations in anatomical proportions or electrophysiological responsiveness. Importantly, while BMI did not significantly predict NCV in either group in our study, limb length consistently appeared as a relevant factor, reinforcing its potential role as a primary anthropometric determinant of conduction velocity.

The results of our multiple linear regression further substantiate the independent role of limb length in predicting NCV. In males, upper limb length was a significant predictor of right median NCV (β = 0.38, p = 0.02), while in females, both upper limb length (β = 0.44, p = 0.01) and age (β = –0.29, p = 0.03) were independently significant. For tibial nerves, lower limb length significantly predicted left tibial NCV in females (β = 0.36, p = 0.04), while in males it showed a borderline association (β = 0.31, p = 0.07). These observations agree with the results of Hennessey et al.¹⁷, who found arm length to be a strong predictor of median nerve conduction even after adjusting for sex and age. Our results also resonate with the work of Simpson et al.²⁰, who studied experimental limb lengthening in animal models and found that internodal segment length increased proportionally with limb length, which partially compensated for expected NCV slowing. However, in human studies like ours, this compensation appears insufficient to completely negate the inverse relationship between limb length and conduction speed. These observations have practical relevance for neurophysiological diagnostics, suggesting that clinicians should consider limb length when interpreting NCV results, particularly in patients with atypically long or short limbs, to avoid misdiagnosing neuropathies based on normative data that do not account for such anatomical variability.

Males, despite having longer limbs, showed higher NCV values compared to females. However, when adjusting for confounding factors such as age, sex, height, and BMI, regression analyses revealed that limb length—particularly upper limb length in the case of median NCV—was an independent predictor of conduction velocity. These findings suggest that anatomical differences in limb lengths may significantly influence NCV measurements and that this effect varies by sex and nerve studied.

From a physiological perspective, longer nerve conduction pathways may lead to slower transmission speeds due to increased internodal distance and potential temporal dispersion. Our study aligns with previous literature indicating that limb or segmental length affects nerve conduction, and also provides new evidence supporting sex-specific and limb-specific patterns in these correlations.

Clinically, this study highlights the importance of considering individual anthropometric variations—especially limb lengths—when interpreting nerve conduction studies. Current normative values used in clinical neurophysiology often do not account for such variations, potentially leading to misinterpretation in individuals with extreme body proportions. Incorporating limb-length adjustments or stratified reference ranges may improve diagnostic accuracy and help avoid over- or under-diagnosis of peripheral neuropathies.

In conclusion, limb length plays a measurable and meaningful role in determining NCV, with upper limb length showing the strongest and most consistent associations. The findings advocate for the inclusion of limb length as a variable in both normative data generation and routine clinical interpretation of nerve conduction studies. Further large-scale, multi-centric studies across diverse populations are warranted to validate these findings and establish population-specific normative values that incorporate anthropometric diversity.

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